JP2000304827A - Non-contact continuity testing method device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely test a connection state by radiating a charged particle beams to a tested circuit network, bringing a detecting conductor connected to a fixed potential close to a part of the tested circuit network, and finding a pattern of a charge distribution of the tested circuit network. SOLUTION: A circuit network 1 formed on a base board 2, for example, is carried out while the base board 2 and a detecting conductor 3 provided apart from the base board 2 are arranged with an electron beam source in the vacuum. The detecting conductor 3 is set to a constant potential as it is grounded. A fixed acceleration voltage electron beam B is applied to irradiate a part of the circuit network 1, the circuit network 1 is charged. If a part radiated by the electron beam B and a position facing the detecting conductor 3 are conducted mutually, electrons (e) gather around the vicinity of the detecting conductor 3, while if a disconnection part F exists, a charge distribution is differentiated from that is connection. For example, determination between a good item and a defective item can be carried out by comparing a charge distribution pattern detected by an electron microscope with a pattern previously provided in a good circuit network 1. An electron beam B may be radiated by an electron microscope.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact continuity inspection method and device capable of non-contact inspection of a connection state of a circuit network.

[0002]

2. Description of the Related Art Generally, a connection state of a circuit network is inspected by
A method is employed in which a contact needle (probe) is brought into contact with an inspection site to check whether or not current flows between two points. Although this method is simple, in recent years, the integration degree of semiconductor parts has increased, and the circuit board on which electronic circuits are mounted has become more complicated and finer. It's getting harder. That is, there is a problem that the speed cannot be increased in the inspection of the connection state using the contact needle.

On the other hand, Japanese Patent Publication No. 5-62700 discloses that a circuit under test is irradiated with an electron beam to charge the circuit under test, and then the electron beam is applied to a desired portion of the circuit under test. Is described, a secondary electron is emitted from a circuit network to be inspected, and a measurement is made of the amount of emitted secondary electrons to identify a charged portion and a non-charged portion. If you apply this technology,
Since the continuity and disconnection of the circuit under test can be detected without touching the circuit under test, even if the circuit under test is complicated and fine, the connection state of the target portion can be detected at high speed without contact. It can be detected with high accuracy.

[0004]

However, according to the technique described in the above publication, secondary electrons are emitted in a state where electric charges are almost uniformly dispersed in a circuit under test.
The amount of secondary electrons emitted is relatively small, and a high-sensitivity detector is required to detect secondary electrons.

The present invention has been made in view of the above circumstances, and an object of the present invention is to control the charge distribution of a network under test by controlling the charge distribution of the network under test without using a highly sensitive detector. It is an object of the present invention to provide a non-contact continuity inspection method and an apparatus thereof that can detect the presence or absence of a non-contact continuity, and consequently detect the connection state of a circuit under test with high accuracy.

[0006]

According to a first aspect of the present invention, a circuit to be inspected which is a continuity test is irradiated with a charged particle beam, and a detection conductor connected to a constant potential is connected to the circuit to be inspected. And comparing the charge distribution pattern of the circuit under test with the charge distribution pattern of a non-defective product to determine the quality of the circuit under test.

According to a second aspect of the present invention, in the first aspect, the charged particle beam is an electron beam.

A third aspect of the present invention uses the pattern of the charge distribution in the vicinity of the detection conductor in a state where the circuit under test is charged with the charged particle beam in the first or second aspect of the invention. The quality is determined.

According to a fourth aspect of the present invention, in the first or second aspect of the present invention, the detection conductors are arranged in close proximity to the respective surfaces of the substrate on which the circuit network to be inspected is formed on both surfaces. It is characterized in that the charged particle beam is irradiated to each of the circuits to be inspected.

According to a fifth aspect of the present invention, in the first or second aspect of the present invention, it is preferable to obtain a charge distribution pattern while changing a relative positional relationship between the circuit under test and the detection conductor. Features.

According to a sixth aspect of the present invention, in the first or second aspect of the present invention, the detection conductor is formed in a lattice shape to cover a region where the circuit under test is formed.

According to a seventh aspect of the present invention, in the first or the second aspect of the present invention, the detection conductor comprises a first sensing line including a plurality of parallel conductors and a plurality of parallel conductors. The first sensing line is formed in a grid by a second sensing line disposed to intersect the first sensing line, and the respective conductors forming the first sensing line and the second sensing line are electrically separated from each other. A charge distribution pattern is obtained by a current flowing between each of the conductors and a ground point electrically separated from each other in the second sensing line.

The invention of claim 8 is characterized in that, in the invention of claim 7, the plurality of charged particle beams are provided, and each of the charged particle beams is irradiated on a different circuit network to be inspected.

According to a ninth aspect of the present invention, in the first aspect of the present invention, the pattern of the charge distribution of the circuit under test is irradiated with a charged particle beam for pattern detection. Thus, a distribution pattern of the amount of secondary electrons emitted is obtained.

According to a tenth aspect of the present invention, in the ninth aspect of the present invention, a charge distribution pattern is obtained by associating the position of the circuit under test with a charge amount, and then a template which is a charge distribution pattern in a good product is obtained. After performing position matching with the template, the degree of coincidence with the template is obtained, and the quality of the circuit under test is determined based on the degree of coincidence.

According to an eleventh aspect of the present invention, in the first to sixth aspects, a current detecting means for detecting a current between the detecting conductor and a ground point is provided, and the charge distribution of the circuit under test is provided. Is obtained as a change pattern of a current detected by the current detection means when the circuit under test is irradiated with a charged particle beam for pattern detection.

According to a twelfth aspect of the present invention, in the eleventh aspect, the charge distribution pattern is detected while the relative position between the irradiation position of the pattern detection charged particle beam and the circuit under test is changed. Features.

According to a thirteenth aspect of the present invention, in the twelfth aspect, the beam source of the charged particle beam for irradiating the circuit under test irradiates the circuit under test immediately after irradiating the charged particle beam. And a beam source for the charged particle beam for pattern detection.

According to a fourteenth aspect of the present invention, in the twelfth or thirteenth aspect, a measured amount corresponding to a charge amount is obtained at a plurality of portions on the surface of the substrate on which the circuit under test is formed, and the measured amount is measured. Is used as a charge distribution pattern.

According to a fifteenth aspect of the present invention, in the invention of the fourteenth aspect, the numerical value sequence is expressed in a matrix format in which each numerical value is associated with each part of the substrate, and the pattern of the charge distribution in the non-defective product and the charge in the inspection object After transforming the matrix so as to match the position with the distribution pattern, the quality is determined based on the degree of coincidence between the two matrices.

According to a sixteenth aspect of the present invention, there is provided a beam source for irradiating a circuit under test with a charged particle beam, a detection conductor connected to a constant potential and approaching a part of the circuit under test, Detecting means for detecting the pattern of the charge distribution of the circuit network; and determining means for determining the quality of the circuit under test by comparing the pattern of the charge distribution of the circuit under test with the pattern of the charge distribution in the non-defective product. It is provided.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) This embodiment is a basic technique of the present invention. In the following, a circuit pattern formed on a substrate 2 as the circuit under test 1 to be tested for continuity as shown in FIG. 1 will be exemplified. In order to detect a disconnection or a short circuit of the circuit under test 1, a detection conductor 3 is arranged so as to be apart from the substrate 2 so as to face a part of the circuit under test 1. The distance between the circuit under test 1 and the detection conductor 3 is set, for example, to 1 mm, and the detection conductor 3 is connected to a constant potential by being grounded. The substrate 2 and the detection conductor 3 are arranged in a vacuum (0.01 Torr or less) together with an electron beam source (not shown) as a beam source. The electron beam source is configured to be able to irradiate the inspection target network 1 with the electron beam B, and irradiates one end of the inspection target network 1 with the electron beam B in the illustrated example.

Here, when the object is irradiated with the electron beam B, the irradiated electron e behaves as follows. That is, the state can be roughly classified into four states: a state where electrons are reflected on the surface of the object, a state where secondary electrons are emitted from the object, a state where the object is charged, and a state where electrons penetrate the object. These behaviors vary depending on the type of the object and the acceleration voltage of the electron beam. When the electron beam B is applied to the metal network 1 to be inspected as in the present embodiment, the acceleration voltage is set to 20 to 25 kV. It has been found that if the circuit under test 1 is charged, the emission of secondary electrons becomes active. Note that an ion beam can be used as a charged particle beam instead of an electron beam. However, since ions have a larger mass than electrons, a sputtering phenomenon that repels atoms in an object occurs depending on an acceleration voltage. Since the sputtering phenomenon occurs when the acceleration voltage is high, it is possible to charge the circuit network 1 to be inspected and activate secondary electrons by setting the acceleration voltage low.

Thus, the acceleration voltage of the electron beam B is set to 20
２５25 kV to set the network under test 1
Is charged. Here, since the detection conductor 3 is at the ground potential, it becomes relatively positive with respect to the circuit under test 1. As a result, if there is electrical continuity between the part to be irradiated with the electron beam B and the opposite part of the detection conductor 3 in the circuit under test 1, as shown in FIG. Is collected near the inspection conductor 3 (the hatching indicates the distribution of the electrons e). 1B, if there is a disconnection portion F between a portion irradiated with the electron beam B and a portion facing the detection conductor 3, electrons from the electron beam B are located near the inspection conductor 3. Since e is not derived, the distribution of the electrons e, that is, the charge distribution, is different from the distribution at the time of conduction. By detecting such a difference in charge distribution between the conduction state and the disconnection state, the quality of the circuit under test 1 can be determined. In other words, the non-defective circuit under test 1
If the pattern of the charge distribution is determined in advance and compared with the detected charge distribution pattern, the quality of the circuit under test 1 can be determined.

An apparatus for detecting the pattern of the charge distribution and judging the quality of the circuit under test 1 is constructed as shown in FIG.
Here, the charge distribution pattern is detected by the electron microscope 11. That is, after the electron beam B is irradiated on the circuit network 1 to be inspected and charged as described above, the electron microscope 1 is charged.
By 1, a portion of the circuit under test 1 near the test conductor 3 is observed. Here, the means for irradiating the inspection target network 1 with the electron beam B may be the electron microscope 11.
The observation result obtained by the electron microscope 11 is captured as an image and written into the frame memory 12. The images stored in the frame memory 12 are stored in a storage device 13 composed of a hard disk device. Among the observation results stored in the storage device 13, the observation result of the non-defective circuit under test 1 is read out as a non-defective data template by the template generation unit 14.

On the other hand, the image to be inspected stored in the frame memory 12 is input to the pre-processing operation unit 15 and is registered with the template. That is, since the image to be inspected usually includes a positional shift due to translation and a positional shift due to rotation with respect to the template,
The position shift is corrected in the preprocessing calculation unit 15. After that, the image to be inspected and the template are compared by the comparison operation unit 16.
And the degree of coincidence between the image to be inspected and the template is determined. Here, to determine the degree of coincidence, a method of counting the number of pixels that do not match between the image to be inspected and the template, or a generalized Hough transform that maps the image to be inspected and the template into a parameter space to obtain a frequency distribution Can be applied. This type of pattern matching technique is well known. When the degree of coincidence is determined in the comparison operation unit 16 in this manner, the inspection determination unit 17 determines the circuit under test 1 according to the degree of coincidence.
Is determined. That is, if the degree of coincidence of the image to be inspected with the template is equal to or greater than the specified value, it is determined that the image is good.

For example, when an image to be inspected as shown in FIG. 3A is obtained and compared with a template T as shown in FIG. Since the pattern P includes a position shift due to parallel movement and a position shift due to rotation, this is corrected by the pre-processing operation unit 15. Since the pattern P ′ of the corrected image is as shown in FIG. 3B, the pattern P ′ of FIG. 3B is compared with the template T of FIG. In the illustrated example, the pattern P ′ to be inspected has one less elliptical pattern than the template T, so the matching degree is low. In this case, the inspection determination unit 17 has a defective product (that is, there is a broken portion F). Will be determined.

In addition, as shown in FIG.
An output device 18 such as a monitor device for displaying a grayscale image stored in the frame memory 12 and a printer for outputting the grayscale image can be connected.

As described above, if the detection conductor 3 is brought close to a part of the circuit under test 1, if the circuit under test 1 is conductive, the electrons e gather near the detection conductor 3. As a result, negative charges concentrate in the vicinity of the detection conductor 3, and when the vicinity of the detection conductor 3 is observed by using the electron microscope 11 as described above, the coverage between the detection conductor 3 and the detection conductor 3 is reduced. A relatively large potential difference occurs between the test network 1 and the test network. In other words, if the area irradiated with the electron beam B and the area near the detection conductor 3 observed by the electron microscope 11 are electrically connected, the amount of secondary electrons emitted by the electron beam of the electron microscope 11 increases. A large contrast can be obtained in the result. Conversely, it can be seen that a portion having a large contrast is electrically connected to a portion irradiated with the electron beam B. In addition, the detection conductor 3
Compared to the case where no circuit is provided, even if the charge amount of the circuit under test 1 is the same, the amount of secondary electrons emitted in the vicinity of the detection conductor 3 at the time of conduction increases, so that it is possible to distinguish between conduction and disconnection. Becomes easier.

In the present embodiment, the position of the detection conductor 3 is fixed, but if the detection conductor 3 is moved along the circuit network 1 to be inspected, the position of the broken portion F can be detected. . Further, the substrate 2 provided with the circuit under test 1 may be moved with respect to the detection conductor 3 instead of moving the detection conductor 3.

(Second Embodiment) In the first embodiment, a configuration for detecting secondary electrons is required separately from the detection conductor 3 in order to detect the charge distribution. In FIG. 4, as shown in FIG. 4, a current detector 4 is provided between the detection conductor 3 and the ground point, and the current flowing through the detection conductor 3 is measured by the current detector 4. Further, after the circuit under test 1 is charged with the electron beam B1, the electron beam B2 is again irradiated onto the circuit under test 1 and the irradiation position of the electron beam B2 is scanned along the circuit under test 1. are doing. That is, the electron beam B2 is scanned as shown by the broken line in FIG. 4, and at this time, more secondary electrons are emitted from the charged portion than from the uncharged portion. When the secondary electrons are emitted, a part of the secondary electrons is captured by the detection conductor 3, so that a current flows through the detection conductor 3. If this current is measured by the current detector 4, it is possible to know whether or not the circuit under test 1 is conducting based on the amount of secondary electron emission.

That is, since electrons accumulate in a portion that is conductive at the position irradiated with the electron beam B1 when the circuit under test 1 is charged, secondary electrons are emitted when the electron beam B2 is next irradiated. Although the amount is large, in a portion that is not conductive to the position irradiated with the electron beam B1 when charging the circuit under test 1, the amount of secondary electrons emitted is reduced even when the electron beam B2 is irradiated next. . Therefore, a current flows through the detection conductor 3 in accordance with the amount of secondary electrons emitted from the circuit under test 1. The current flowing through the detection conductor 3 is set so that the acceleration voltage of the electron beams B1 and B2 is 20 to 25.
kV, and the distance between the circuit under test 1 and the detection conductor 3 is 1
When it is set to 10 mm, it is 10 to 1000 pA, and the current detector 4 may be used to detect such a current.

Thus, as shown in FIGS. 4A and 5A, a broken portion F is formed between the irradiation position of the electron beam B1 in the circuit under test 1 and the portion facing the detection conductor 3. When present, since the network under test 1 is hardly charged, the current measured by the current detector 4 is as shown in FIG.
As shown in (b), regardless of the irradiation position of the electron beam B2, it is substantially constant at a portion other than the position where the disconnection portion F and the detection conductor 3 are arranged. At the disconnection portion F, even if the electron beam B2 is irradiated, no secondary electrons are emitted. Therefore, almost no current flows through the current detector 4, and when the detection conductor 3 is irradiated with the electron beam B2, a current due to the electron beam B2 is generated. Since the current flows through the current detector 4, the current increases.

On the other hand, as shown in FIGS. 4 (b) and 6 (a), when the irradiation position of the electron beam B1 is electrically connected to the portion facing the detection conductor 3, the electron beam B2 is As the distance approaches 3, the change pattern of the current detected by the current detector 4 becomes lower than that of other parts as shown in FIG. It is considered that such a phenomenon occurs because more electrons are emitted near the detection conductor 3 than at other portions.

As described above, it is determined whether the electron beam B2 is conductive or disconnected based on the change pattern of the current value measured by the current detector 4 when the electron beam B2 is scanned along the circuit under test 1. It becomes possible.

In this embodiment, the electron beam B1 for charging the circuit under test 1 is irradiated onto the circuit under test 1, and then the electron beam B2 is scanned along the circuit under test 1 to emit secondary electrons. However, as shown in FIG.
Even when scanning with the electron beam B2 is performed while irradiating the electron beam B1, the current value measured by the current detector 4 shows the same change as described above. Therefore, by simultaneously irradiating the circuit under test 1 with the electron beam B1 and the electron beam B2, the inspection time can be reduced.
Further, the same electron beam source is used for the electron beam B1 and the electron beam B2, and the electron beam B1 is transmitted to the circuit network 1 to be inspected.
The electron beam B2 may be irradiated immediately after the irradiation. Other configurations and operations are the same as those of the first embodiment.

(Third Embodiment) This embodiment is different from FIG.
As described above, the circuit network 1 to be inspected is formed on both surfaces of the substrate 2, and the detection conductors 3 are also arranged so as to face both the front and back surfaces of the substrate 2. Each detection conductor 3 can be moved to an arbitrary position along the surface of the substrate 2. Other configurations and operations are the same as those of the second embodiment.

Therefore, by charging the circuit under test 1 with the electron beam B1 and scanning the electron beam B2 while changing the position of the detection conductor 3, the conduction of the circuit under test 1 at an arbitrary position on the substrate 2 can be achieved. And cutting can be inspected. Further, as described above, the detection conductors 3 are arranged so as to face the front and back surfaces of the substrate 2 respectively, so that
When inspecting the continuity of the circuit under test 1 provided on the front and back of the substrate 2, the electron beam B <b> 2 is scanned along the circuit under test 1 connected to the front and back to detect the front and back of the substrate 2. If the current is detected by the current detector 4 connected to the conductor 3,
It is possible to inspect the continuity between the front and back according to the current change pattern. In addition, since the circuit under test 1 on the front and back of the substrate 2 can be inspected at the same time, the time required for the inspection can be reduced as compared with the case where the inspection is performed separately.

(Fourth Embodiment) In the above-described embodiment, the detection conductor 3 is formed in a linear shape. However, in this embodiment, as shown in FIG. 3
A lattice-like material that covers a region where the circuit under test 1 is formed (that is, the substrate 2) is used. The illustrated detection conductor 3 includes a first sensing line 3a formed of a plurality of parallel conductors and a second sensing line formed of a plurality of parallel conductors and arranged orthogonal to the first sensing line 3a. 3b. The conductors forming the first sensing line 3a and the second sensing line 3b are electrically separated from each other, and the current detector 4 is connected between each conductor and a ground point (in FIG. Although the current detector 4 is connected only to the conductor of the first sensing line 3a,
The current detector 4 is also connected to the conductor b). However, the ground points of the first sensing line 3a and the second sensing line 3b are separated from each other, so that no current flows between the first sensing line 3a and the second sensing line 3b. .

In this configuration, after the circuit under test 1 is charged by the electron beam B1, the charge distribution at each part of the substrate 2 is detected without moving the detection conductor 3 only by scanning the electron beam B2. be able to. Other configurations and operations are the same as those of the second embodiment.

In the configuration of the present embodiment, if the plurality of electron beams B2 are scanned so as not to interfere with each other (ie, not to irradiate the same circuit under test 1 with the plurality of electron beams B2 at the same time), Inspection can be performed in a shorter time than when one electron beam B2 is scanned.

(Fifth Embodiment) In the present embodiment, FIG.
Although the detection conductors 3 in the form of a lattice are used as shown in FIG. 5, instead of electrically separating the conductors as in the fourth embodiment, the conductors forming the lattice are electrically connected to each other. , A current detector 4 is provided between one point of the detection conductor 3 and a ground point. The other configuration is the same as that of the fourth embodiment. If the electron beam B2 is scanned, it is possible to detect the charge distribution at the scanning position without moving the detection conductor 3.

In the present embodiment, the detection conductors 3 are respectively arranged opposite to the front and back surfaces of the substrate 2, and the electron beams B 2 are respectively applied to the circuit under test 1 formed on each of the front and back surfaces of the substrate 2. Irradiation. In this configuration, the current detectors 4 are shared by both the detection conductors 3. However, if the current detectors 4 are provided on the respective detection conductors 3, the front and back surfaces of the substrate 2 are simultaneously irradiated with the electron beam B <b> 2. Inspection can be performed. Other configurations and operations are the same as those of the second embodiment.

(Sixth Embodiment) In this embodiment, a technique for judging pass / fail of a circuit under test 1 after detecting a charge distribution on a substrate 2 will be described by taking the fourth embodiment as an example. I do. That is, the grid-like detection conductor 3 is used as in the fourth embodiment.
Scanning is performed in a direction parallel to the second sensing line 3b between a pair of conductors adjacent to the sensing line 3b (a broken line in FIG. 10 indicates a locus for scanning the electron beam B2, and the broken line is hereinafter referred to as a scanning line). When the grid-like detection conductor 3 is used and the electron beam B2 is scanned as described above, the current value when the irradiation position of the electron beam B2 approaches each conductor of the first sensing line 3a is determined by the current value of the circuit under test 1 It changes depending on the state of. Then, electron beam B
The reference current value i0 is set based on the current value when the irradiation position 2 is away from the conductor, and the minimum value of the current value and the reference current value when the irradiation position of the electron beam B2 approaches each conductor. The current difference from i0 is determined as a measured amount. Also,
The obtained current difference is handled as a matrix in association with the position of the scanning line of the electron beam B2 and the position of the conductor of the first sensing line 3a.

For example, in the example of FIG.
Are three scanning lines, and the first sensing line 3a is 4
Because it is a book, it is possible to express the numerical sequence of the obtained current difference as a matrix of 3 rows and 4 columns. Now, FIG.
If each current difference is obtained as shown in FIG. 11, it can be handled as a matrix as shown in FIG. If each element of the matrix obtained in this way is treated as a pixel, the above-described matrix processing can be performed using an image processing apparatus capable of handling a grayscale image. Further, if each element of the matrix is associated with the density of the pixel, the state of the circuit under test 1 can be visualized.

Since the above-mentioned matrix reflects the connection state of the circuit under test 1, the pass / fail judgment can be made by applying the pattern matching technique used in the image processing technique to the above-mentioned matrix. That is, the circuit under test 1
If the matrix of the non-defective circuit is determined as a template and the degree of coincidence with the matrix of the circuit under test 1 to be inspected is detected, the quality of the circuit under test 1 can be determined. Now, it is assumed that each element of the matrix is represented by a gray-scale image having pixels, and that a gray-scale pattern as shown in FIG. I do. In FIG. 12, one cell corresponds to one element (or pixel) of the matrix, and the hatching pitch in each cell represents the density. 12 (a) and 12 (b), the light and shade pattern of FIG.
Since (b) has a missing portion in the upper center, it can be determined to be defective. Here, the positions of the non-defective pattern (template) and the target pattern are usually shifted, so that in the case of pattern matching, the target pattern is aligned by performing a parallel or rotational movement. Need to do. The pattern matching is performed after such positioning, and the pattern matching is performed as described in the first embodiment.
A technique for obtaining the area of the mismatched portion by superimposing the elements of the matrix and a technique using a generalized Hough transform for mapping a grayscale image to a parameter space are applied. These techniques are well known in the image processing art, and thus description thereof is omitted here. Other configurations and operations are the same as those of the fourth embodiment.

(Seventh Embodiment) This embodiment relates to a sixth embodiment.
In the same way as in the sixth embodiment, the pass / fail judgment is made by comparing the non-defective pattern with the target pattern. In this embodiment, however, the difference in the current difference as in the sixth embodiment is used. The pass / fail judgment is made without any change. The technology of the present embodiment is applicable to the inspection conductor 3 shown in the fifth embodiment.

That is, when the grid-like detection conductors 3 are arranged as shown in FIG. 13A and the circuit under test 1 is charged using the electron beam B2, for example, as shown in FIG. Electrons are concentrated in the vicinity of each conductor of the conductor 3 (shaded portions indicate electron concentration portions). Here, the electron density differs depending on the positional relationship between the circuit under test 1 and the test conductor 3, but in the present embodiment, the electron density itself is ignored, and the shape of a portion having a high electron density is extracted as a template. For example, since the electron density distribution can be detected by observation using an electron microscope, if the obtained electron density is binarized by applying an appropriate threshold value, as shown in FIG. It is possible to extract the pattern of the electron concentration portion in a simple manner.

Now, it is assumed that the pattern when the circuit under test 1 is a non-defective product has the form shown in FIG. On the other hand, if the disconnection portion F as shown in FIG. 15A is generated in the circuit under test 1 to be inspected, the pattern P of the electron concentration portion becomes as shown in FIG.
(B). Here, since the pattern to be inspected is often displaced from the non-defective pattern (template), a parallel or rotational movement is appropriately performed to obtain a pattern P ′ as shown in FIG. ,afterwards,
This is compared with the template T shown in FIG. In the configuration of the present embodiment, after the pattern P to be inspected is aligned with the template T, the number of unmatched pixels is obtained (that is, the difference is obtained), and the number of pixels is determined using an appropriate threshold. Pass / fail can be determined. In the example shown in FIG. 16, since there is a missing part for the non-defective pattern in the upper right part of the pattern to be inspected, it can be determined as defective.

FIG. 17 shows the processing procedure of this embodiment. First, when data of a good pattern (template) already exists (S1), the template is read (S2). If the template does not exist, a test object having the non-defective circuit network 1 is input (S3, S4), and the charge distribution of the circuit network 1 is detected as described above (S5). Then, a pattern characteristic of the charge distribution is extracted (S6).

Next, after the circuit under test 1 to be tested is turned on (S7, S8), a charge distribution is detected for the circuit under test 1 to be tested (S9). Is extracted (S10). The pattern extracted for the non-defective product (or the data of the non-defective product) and the pattern extracted for the inspection target are collated (S11), and the difference between the two is obtained (S12). By comparing the difference with an appropriate threshold value, it is possible to determine the quality of the circuit under test 1 to be tested (S13). The above processing is repeated until there is no inspection target (S14).

[0052]

According to a first aspect of the present invention, a charged particle beam is irradiated to a circuit under test to be subjected to a continuity test.
The detection conductor connected to the constant potential is brought close to a part of the circuit under test, and the quality of the circuit under test is judged by comparing the pattern of the charge distribution of the circuit under test with the pattern of the charge distribution of a good product. Therefore, if the charge distribution of the circuit under test can be changed according to the position of the detection conductor and the charge is detected at a portion where the charges are concentrated, the charge can be detected without using a highly sensitive detector. There is an advantage that the distribution can be detected. That is, the connection state of the circuit under test can be detected with high accuracy.

According to a second aspect of the present invention, in the first aspect of the present invention, the charged particle beam is an electron beam, which can be realized by a simple device and can irradiate an area smaller than other charged particles. Will be possible.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the quality is evaluated by using a charge distribution pattern in the vicinity of the detection conductor when the circuit under test is charged with the charged particle beam. The determination of the charge distribution is made easier by preliminarily applying a charge to the circuit under test from the determination.

According to a fourth aspect of the present invention, in the first or the second aspect of the present invention, the detection conductors are respectively arranged close to the respective surfaces of the substrate having the circuit network to be inspected formed on both surfaces thereof, and each of the inspection circuits is inspected. Since a charged particle beam is applied to each of the circuit networks, it is possible to inspect both side patterns at the same time, which leads to a reduction in inspection time.

According to a fifth aspect of the present invention, in the first or second aspect of the invention, the charge distribution pattern is obtained while changing the relative positional relationship between the circuit under test and the detection conductor. It is possible to specify a disconnection point in the circuit network.

According to a sixth aspect of the present invention, there is provided a method according to the first or second aspect, wherein the detecting conductor is formed in a lattice shape covering a region where the circuit under test is formed. By using the grid-like detection conductor, it is possible to specify a broken portion of the circuit under test without changing the position of the detection conductor.

According to a seventh aspect of the present invention, in the first or the second aspect of the present invention, the detection conductor comprises a first sensing line comprising a plurality of parallel conductors and a plurality of parallel conductors. The first sensing line and the second sensing line are electrically separated from each other and formed in a lattice by the second sensing line disposed to intersect the first sensing line. The pattern of the charge distribution is determined by the current flowing between the ground and the respective conductors which are electrically separated from each other at the second sensing line, and the current flowing through the first sensing line and the second sensing line is determined. The detection makes it possible to know the distribution of charges in the circuit under test, and the configuration for detecting the charge distribution is simplified. There is.

According to an eighth aspect of the present invention, in accordance with the seventh aspect of the present invention, there are provided a plurality of charged particle beams, and each charged particle beam is irradiated to a different circuit network to be inspected. The use of a beam leads to a reduction in inspection time.

According to a ninth aspect of the present invention, in the first to sixth aspects of the present invention, the pattern of the charge distribution of the circuit under test is formed by irradiating the circuit under test with a charged particle beam for pattern detection. Since the distribution pattern of the emission amount of the secondary electrons is obtained, an electron microscope or the like can be used as a detector.

According to a tenth aspect of the present invention, in the ninth aspect of the present invention, a charge distribution pattern is obtained by associating a position of a circuit network to be inspected with a charge amount. After performing the alignment, the degree of coincidence with the template is determined, and the acceptability of the circuit under test is determined based on the magnitude of the degree of coincidence. Since the position of the comparison control is aligned, the degree of coincidence is determined with high accuracy. can do.

According to an eleventh aspect of the present invention, in the first to sixth aspects, a current detecting means for detecting a current between the detecting conductor and the ground point is provided, and the charge distribution pattern of the circuit under test is provided. Is obtained as a change pattern of the current detected by the current detection means when the charged particle beam for pattern detection is irradiated to the circuit under test, so that the circuit under test can be configured with a simple configuration using a detector for detecting the current. It is possible to detect the charge distribution.

According to a twelfth aspect of the present invention, in accordance with the eleventh aspect of the present invention, the charge distribution pattern is detected while changing the irradiation position of the charged particle beam for pattern detection and the relative position between the circuit to be inspected. It is possible to specify the position of the disconnection in the inspection network.

According to a thirteenth aspect of the present invention, in the twelfth aspect, the beam source of the charged particle beam for irradiating the circuit to be inspected irradiates the circuit to be inspected immediately after irradiating the charged particle beam. Since it is also used as a beam source for the charged particle beam, it is not necessary to separately provide a beam source for charging the circuit to be inspected and a beam source for detecting the charge distribution, leading to a reduction in cost.

According to a fourteenth aspect of the present invention, in the twelfth or thirteenth aspect, a measured amount corresponding to a charge amount is obtained at a plurality of portions on the surface of the substrate on which the circuit under test is formed, and the measured amount is determined. Since the sequence of numerical values is used as the pattern of the charge distribution, it is possible to judge pass / fail by comparing the sequence of numerical values, and the accuracy of pass / fail judgment is increased.

According to a fifteenth aspect of the present invention, in the invention of the fourteenth aspect, the numerical value sequence is expressed in a matrix form in which each numerical value is associated with each part of the substrate, and the pattern of the charge distribution in the non-defective product and the charge distribution in the inspection object are obtained. After converting the matrix so as to match the position with the pattern, pass / fail is determined from the degree of coincidence of both matrices.Since the charge distribution pattern is expressed in a matrix, it is possible to perform translation or Rotational movement and the like can be easily performed, and alignment is easy.

A sixteenth aspect of the present invention provides a beam source for irradiating a circuit under test with a charged particle beam, a detection conductor connected to a constant potential and approaching a part of the circuit under test, Detecting means for detecting the charge distribution pattern of the circuit under test, and determining means for judging the quality of the circuit under test by comparing the pattern of the charge distribution of the circuit under test with the pattern of the charge distribution in the non-defective product. Yes, it is possible to change the charge distribution of the circuit under test according to the position of the detection conductor, and if the charges are detected at the site where the charges are concentrated,
There is an advantage that the distribution of electric charges can be detected without using a highly sensitive detector. That is, the connection state of the circuit under test can be detected with high accuracy.

[Brief description of the drawings]

FIGS. 1A and 1B show a first embodiment of the present invention, wherein FIG. 1A is an explanatory diagram of a non-defective product and FIG. 1B is an explanatory diagram of a defective product.

FIG. 2 is a block diagram of an apparatus used in the embodiment.

FIG. 3 is an operation explanatory diagram of the above.

4A and 4B show a second embodiment of the present invention, in which FIG. 4A is an explanatory diagram of a defective product, and FIG. 4B is an explanatory diagram of a non-defective product.

FIG. 5 is an operation explanatory view of a defective product using the above.

FIG. 6 is an operation explanatory diagram of a non-defective product using the above.

FIG. 7 is an explanatory diagram showing a third embodiment of the present invention.

FIG. 8 is an explanatory diagram showing a fourth embodiment of the present invention.

FIG. 9 is an explanatory diagram showing a fifth embodiment of the present invention.

FIG. 10 is an operation explanatory view showing a sixth embodiment of the present invention.

11A and 11B show an example of the above, and FIG.
(B) is an explanatory diagram of a matrix expression.

FIG. 12 is an operation explanatory view of the above.

13A and 13B show a seventh embodiment of the present invention, in which FIG. 13A is an explanatory diagram showing an arrangement example, and FIG. 13B is an explanatory diagram showing a state of charge distribution.

FIG. 14 is an explanatory diagram showing a non-defective charge distribution in the above.

FIG. 15A is an explanatory diagram showing a circuit under test which is a defective product in the above, and FIG. 15B is an explanatory diagram showing a charge distribution of the defective product.

FIG. 16A is an explanatory diagram showing a charge distribution of a defective product in the above, and FIG. 16B is an explanatory diagram showing a charge distribution of a non-defective product in the above.

FIG. 17 is an operation explanatory diagram showing a processing procedure of the above.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inspection network 2 Substrate 3 Test conductor 3a 1st sensing line 3b 2nd sensing line 4 Current detector B Electron beam B1, B2 Electron beam P, P 'pattern T template

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinji Hatazawa 1048 Kazuma Kadoma, Kadoma-shi, Osaka Matsushita Electric Works Co., Ltd. (72) Inventor Kazunari Yoshimura 1048 Kadoma Kadoma Kadoma-shi, Osaka Pref. F-term (Reference) 2G011 AA01 AB09 AC21 AD01 AE01 2G014 AA02 AA03 AB59 AC11 AC18 2G032 AA00 AB00 AB01 AF08 AH02 AJ06 AK04 4M106 AA08 BA02 CA08 DE09 DH07 DH24 DH33 DJ18 DJ20 DJ21 DJ27

Claims (16)

[Claims] A circuit to be inspected, which is a continuity inspection object, is irradiated with a charged particle beam, and a detection conductor connected to a constant potential is brought close to a part of the circuit to be inspected; A non-contact continuity inspection method characterized in that the quality of a circuit under test is judged by comparing the charge distribution pattern of the net with the charge distribution pattern of a good product. 2. The non-contact continuity inspection method according to claim 1, wherein said charged particle beam is an electron beam. 3. The method according to claim 1, wherein the pass / fail judgment is made using a charge distribution pattern near the detection conductor when the circuit under test is charged with the charged particle beam. 2. The non-contact continuity inspection method according to 2. 4. The circuit according to claim 1, wherein the detection conductors are arranged close to the respective surfaces of the substrate on which both sides of the circuit to be inspected are formed, and each of the circuits to be inspected is irradiated with the charged particle beam. The non-contact continuity inspection method according to claim 1 or 2, wherein 5. The non-contact continuity test according to claim 1, wherein a charge distribution pattern is obtained while changing a relative positional relationship between the circuit under test and the detection conductor. Method. 6. The non-contact continuity inspection method according to claim 1, wherein the detection conductor is formed in a lattice shape covering a region where the circuit under test is formed. 7. The sensing conductor includes a first sensing line including a plurality of parallel conductors and a second sensing line including a plurality of parallel conductors and arranged to intersect the first sensing line. The conductors forming the first sensing line and the second sensing line are formed in a grid pattern by the lines and are electrically separated from each other, and the ground points electrically separated from each other in the first sensing line and the second sensing line 7. A non-contact continuity inspection method according to claim 6, wherein a charge distribution pattern is obtained by a current flowing between the conductor and each conductor. 8. The charged particle beam includes a plurality of beams,
The non-contact continuity inspection method according to claim 7, wherein each charged particle beam is irradiated to a different circuit network to be inspected. 9. A pattern of a charge distribution of the circuit under test is obtained as a distribution pattern of an emission amount of secondary electrons by irradiating the circuit under test with a charged particle beam for pattern detection. The non-contact continuity inspection method according to any one of claims 1 to 6. 10. A pattern of a charge distribution is obtained by associating the position of the circuit under test with a charge amount, and the position of the charge distribution pattern in a non-defective product is matched with the template after alignment with the template. The non-contact continuity inspection method according to claim 9, wherein the degree of coincidence is determined, and the quality of the circuit under test is determined based on the degree of coincidence. 11. A current detection means for detecting a current between the detection conductor and a ground point, wherein a charge distribution pattern of the circuit under test is charged to the circuit under test by charged particles for pattern detection. The non-contact continuity inspection method according to claim 1, wherein the non-contact continuity inspection method is obtained as a change pattern of a current detected by the current detection unit when a beam is irradiated. 12. The non-contact continuity inspection according to claim 11, wherein a charge distribution pattern is detected while changing a relative position between an irradiation position of the charged particle beam for pattern detection and a circuit under test. Method. 13. The charged particle beam beam source for irradiating the circuit under test, wherein the beam source of the charged particle beam irradiates the circuit under test immediately after irradiating the charged particle beam. 13. The non-contact continuity inspection method according to claim 12, wherein the method is also used. 14. The method according to claim 1, wherein a measured amount corresponding to the charge amount is obtained at a plurality of positions on the surface of the substrate on which the circuit under test is formed, and a numerical sequence of the measured amount is used as a charge distribution pattern. The non-contact continuity inspection method according to claim 12 or 13. 15. The numerical value sequence is expressed in a matrix format in which each numerical value is associated with each part of the substrate, and is formed into a matrix so that the positions of the charge distribution pattern in the non-defective product and the charge distribution pattern in the inspection object are aligned. 15. The non-contact continuity inspection method according to claim 14, wherein the pass / fail is determined from the degree of coincidence between the two matrices after the conversion. 16. A beam source for irradiating a network under test with a charged particle beam, a detection conductor connected to a constant potential and approaching a part of the network under test, and a charge distribution of the network under test. Detecting means for detecting the pattern of the circuit under test, and determining means for judging the quality of the circuit under test by comparing the pattern of the charge distribution of the circuit under test with the pattern of the charge distribution of non-defective products, Non-contact continuity inspection device.