JPH023254A - Board tester by electron beam - Google Patents

Abstract

PURPOSE:To make it possible to shorten inspection time with small size by rotating a sample 90 deg. at a time with the axis vertical to the center of the samples to be taken four pieces at a time as a rotation axis, and rotating the scanning pattern 90 deg. at a time interlocking with this rotation. CONSTITUTION:This is provided with a rotation means 24 which rotates a sample 9 90 deg. at a time with the axis vertical to the center of the samples to be taken four pieces at a time as a rotation axis, and a scanning pattern rotation means 25 which rotates the scanning pattern 90 deg. at a time interlocking with the rotation of 90 deg. at a time of the rotation means 24. In this case, the rotation means 24 consists of a rotation table 21, a driving motor 23 and a controller 14. Also, the scanning pattern rotation means 25 consists of an electron beam deflecting circuit 8 and a controller 14. And the irradiation is done while scanning each face of the sample 9 to be taken for four faces separately in sequence within a vacuum sample room 15 with electron beam 3 by means of an electric bean scanning means 26. And the sample 9 is observed by detecting secondary electrons 4 emitted from the sample 9. The electron beam scanning means 26 consists of an electron gun 1 and an electric lens system 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electron beam tester for substrates used for testing the characteristics of semiconductor chips such as thin film transistor array substrates for liquid crystal panels.

[Conventional technology]

In recent years, semiconductor chips have been widely used in the semiconductor manufacturing process.

By conducting a 100% inspection of the characteristics of wafers, the company aims to prevent defective products from being sent to the assembly process and reduce assembly man-hours and material loss. The aim is to improve yield by discovering defective lots at an early stage and checking process defects.

In this way, in order to inspect the characteristics of semiconductor chips in the semiconductor manufacturing process, we have developed an electron beam for substrates with a high throughput that can inspect many semiconductor chips at once using a scanning electron microscope with a large scanning range. Testers are needed.

A conventional electron beam tester for substrates of this type will be explained with reference to FIGS. 5 and 6.

As shown in Fig. 5, this electronic beam tester for substrates has the following features:
In a reduced pressure sample chamber (not shown), an electron beam 53 is sequentially applied to each surface A', B', C', and D' of a four-sided sample 59 made of a thin film transistor array substrate for a liquid crystal panel by an electron beam scanning means 61. The sample 59 is irradiated while scanning, and the secondary electrons 54 emitted from the sample 59 are detected.
are being observed. The electron beam scanning means 61 includes an electron gun 51 and an electron lens system 52.

The operation of this electron beam tester for substrates will be explained in detail below with reference to FIGS. 5 and 6.

A four-sided sample 59 is placed on an X-Y table 60 in a reduced pressure sample chamber. Thermionic electrons generated by the electron gun 51 are accelerated by the electron lens system 52.

The electron beam 53 is deflected and focused on the surface of the sample 59.
becomes. At this time, the electron lens system 52 is controlled by the electron beam deflection circuit 58 and irradiates the surface of the sample 590 with the electron beam 53 while scanning it.

Secondary electrons 54 are emitted from the surface of the sample 59 irradiated with the electron beam 53 . This secondary electron 54 is captured by a secondary electron multiplier 55 and accelerated.

Further, the secondary electron multiplier 55 converts the accelerated secondary electrons 54 into a secondary electron signal SI+, and applies it to the amplifier 56. The amplifier 56 amplifies the secondary electron signal S11 input from the secondary electron multiplier 55 and applies it to the monitor 57. The monitor 57 displays the secondary electronic signal S amplified by the amplifier 56.

Further, the sample 59 is sequentially moved from the A' plane to the D' plane by the X-Y table 60 and is irradiated with the electron beam 53.

To irradiate each surface A' to D' of the sample 59 with the electron beam 53, as shown in FIG. irradiate while At this time, the scanning area of the electron beam 53 is approximately 5 V.
Because it is narrow (m x 5 rym), the arrow Z' shown in Fig. 6
The electron beam 53 is scanned over a part of the A' surface of the sample 59 as shown in FIG. Then, the X-Y table 60 is moved in the direction of the arrow X' or Y' shown in Figure 6, and the electron beam 53 is scanned again. In this way, the electron beam 53 is scanned over the entire A' plane while repeating the scanning of the electron beam 53 and the movement of the The table 60 is moved and the B' plane of the sample 59 is placed under the electron gun 51. Then, similarly to the A' plane, the scanning of the electron beam 53 and the movement of the X-Y table 60 are repeated on the B' plane so that the entire B' plane is scanned with the electron beam 53. Furthermore, the electron beam 53 scans the C' plane and the D' plane sequentially in the same manner.

In addition, the sample 59 consisting of a thin film transistor array for a liquid crystal panel has a size of 60fi x 501 on each surface A' to D'.
m, and the overall dimensions of sample 59 are 152 mm x 152 a
+m, which is large. Therefore, in this electron beam tester for substrates, one of the
The robot performs about 120 movements per session.

[Problem to be solved by the invention]

This conventional electron beam tester for substrates sequentially moves the X-Y table 60 in the X direction and the Y direction in order to move the four-sided sample 59 between each surface A' to D'. The problem was that it took a long time. As a result, there is a problem that the inspection time becomes long and it is not possible to inspect all the semiconductor chips during the manufacturing process.

In addition, as mentioned above, the dimensions of sample 59 are 152×1
The electron beam 5 is large at 52m+++ and covers the entire area of the sample 59.
In order to scan 3, a large XY table 60 is required. As a result, the volume of the sample chamber becomes large, the exhaust system becomes large-scale, and the apparatus becomes large-sized.

Therefore, an object of the present invention is to provide an electron beam tester for substrates that is small in size and can shorten inspection time.

[Means to solve the problem]

The electron beam tester for substrates of the first invention is provided with a rotation means that rotates the sample in 90 degree increments with a vertical axis as the rotation axis at the center of the four chamfers, and in conjunction with the rotation in 90 degree increments, the scanning pattern is rotated in 90 degree increments. The present invention is characterized in that it is provided with a scanning pattern rotation means that rotates the scanning pattern by degrees.

The electron beam tester for substrates according to the second aspect of the invention has an electron beam scanning means having a rotation axis of 90 mm with an axis perpendicular to the center of the four chamfers as the rotation axis.
The present invention is characterized in that a rotation means for rotating the scanning pattern by 90 degrees is provided, and a scanning pattern rotation means is provided for rotating the scanning pattern by 90 degrees in conjunction with the rotation by 90 degrees.

[For production]

According to the configuration of the first invention, the rotating means rotates the sample by 90 degrees around the center of the four chamfers with the vertical axis as the rotation axis, and the scanning pattern rotating means interlocks with the rotation of the rotating means by 90 degrees. Since the scanning pattern of the electron beam is rotated by 90 degrees, it is possible to move each side of a four-sided sample by 111N degrees by simply rotating the sample by 90 degrees, and each side of the sample can be moved in the same direction. The electron beam can be scanned from Therefore, compared to the case where the table is moved in the XY force direction, the time required to move the table is significantly shortened, and the space for moving the table may be narrower.

According to the configuration of the second invention, instead of the sample of the first invention, the electron beam scanning means is rotated in 90 degree increments with an axis perpendicular to the center of the four chamfers of the sample as the rotation axis. It is possible to scan each surface with an electron beam from the same direction. This results in an effect similar to that of the first invention.

〔Example〕

An embodiment of the electron beam tester for substrates according to the present invention will be described with reference to FIGS. 1 to 4.

This electronic beam tester for substrates, as shown in Figure 1,
Sample 9 was rotated at 90° with the axis perpendicular to the center of the four chamfers as the rotation axis.
A rotation means 24 for rotating the scanning pattern by 90 degrees is provided, and a scanning pattern rotation means 25 for rotating the scanning pattern by 90 degrees in conjunction with the rotation of the rotation means 24 by 90 degrees is provided. In this case, the rotating means 24 includes a morph 23 for driving the rotating table 213 and a controller 14.

Further, the scanning pattern rotation means 25 includes an electron beam deflection circuit 8 and a controller 14.

Then, within the reduced pressure sample chamber 15, each surface of the four-sided sample 9 is sequentially irradiated with the electron beam 3 while being scanned by the electron beam scanning means 26.

The sample 9 is then observed by detecting the secondary electrons 4 emitted from the sample 9. The electron beam scanning means 26 is composed of an electron gun 1 and an electron lens system 2.

This electron beam tester for substrates will be explained in detail below with reference to FIGS. 1 and 2.

A four-sided sample 9 is placed in the sample chamber 15 on a rotary table 21.
is placed above. The sample chamber 15 has a turbo pump 1
8, the degree of vacuum is maintained at about 10-5 torr. The area around the electron gun 1 is also heated by 10-'t by the ion pump 20.
It is maintained at a vacuum level of orr.

A signal output from a drive circuit 13 that drives a thin film transistor for a liquid crystal panel is applied to the sample 9 via a probe 22.

Thermionic electrons generated by the electron gun 1 are accelerated and deflected by the electron lens system 2 and converged on the surface of the sample 9 to become an electron beam 3. This focused electron beam 3 has a beam diameter of, for example, φ5 μm to 10 μm, and a beam current of 104 A to 10 μm.
The electron beam 3 is irradiated with the electron beam 3 while scanning the surface of the sample 9 by the electron lens system 2.

In addition, in order to scan the electron beam 3 on one side of the metal body of the four-sided sample 9 at a time, the scanning area of the electron beam 3 is 666.
+++mX66+mn is required. For this reason, the electron gun 1
For example, if the working distance between sample 9 and sample 9 is approximately 400
It is set to mn+. In this way, one surface of the sample 9 is scanned by the electron beam 3 at one time.

By irradiating the electron beam 3, a secondary electron beam 4 is emitted from the sample 9 with an intensity corresponding to the potential distribution on the surface of the sample 9. At this time, the amount of secondary electrons 4 emitted from the sample 9 is:
There are relatively more places at a potential than there are places at positive potential.

Therefore, the surface potential of the sample 9 can be detected based on the amount of secondary electrons 4 emitted.

The secondary electrons 4 emitted from the sample 9 are transferred to the secondary electron multiplier 5
is captured and accelerated. The secondary electron multiplier tube 5 is
The accelerated secondary electrons 4 are converted into a secondary electron signal S, which is applied to an amplifier 6. The amplifier 6 amplifies the secondary electronic signal S1 and applies it to the analog-to-digital conversion circuit 11. analog·
The digital conversion circuit 11 converts the amplified 2
The next electronic signal S is inputted, converted into 8-bit digital data at predetermined time intervals, and added to the memory circuit 12.

The memory circuit 12 is an analog/digital conversion circuit 11
A digitized secondary electron signal S inputted from is recorded as a secondary electron image. Then, if necessary, the secondary electron image recorded in the memory circuit 12 is displayed on the monitor 7 as a potential contrast image, and the sample 9 is observed.

In addition, the driving of the sample 9 consisting of a thin film transistor array for a liquid crystal panel, the scanning of the electron beam 3, and the rotating table 2
Since it is necessary to synchronize the rotation of the electron beam deflection circuit 8. Analog-digital conversion circuit 11. tj, the crystal panel thin film transistor drive circuit 13 and the motor 23 for driving the rotary table 21 are synchronously controlled by the controller 14.

Reference numeral 16 indicates a preparatory chamber, in which preliminary evacuation is performed to improve throughput, and the degree of vacuum in the preparatory chamber 16 is raised from the atmosphere to the order of 10-'torr at high speed by a pump 19 consisting of a rotary pump and a turbo pump. .

Then, the sample 9 is transferred to the sample chamber 15 through the gate 17.

Next, the scanning pattern rotation means 25 and the rotation means 24 will be explained.

The rotating means 24 is rotated by a controller 14 controlling a driving motor 23 connected to the rotating table 21.
Freely position the rotary table 21 in degrees.
Rotate in 0 degree increments.

As shown in FIG. 2, the center of the four chamfers of the sample 9 is placed at the center of the rotary table 21, and
is rotated by 90 degrees so that each surface A to D of the sample 9 is sequentially moved under the electron gun 1. In this way, the rotating means 24 rotates the sample 9 by 90 degrees around the center of the four chamfers, with the vertical axis as the rotation axis.

On the other hand, when the A side of the sample 9 is placed under the electron gun 1, the electron beam scanning means 26 directs the electron beam 3 to the A side as indicated by the arrow X shown in FIG. 3(a). Scanning is performed by horizontally deflecting in the child direction and vertically deflecting in the child direction of arrow Y. Next, when the rotary table 21 is rotated 90 degrees in the direction of the arrow a and the B plane is moved below the electron gun 1, the scanning pattern rotation means 25 rotates the electron beam 3 to the A plane with respect to the sample 9. The scanning pattern is rotated 90 degrees so that it is scanned from the same direction as the electron beam 3.
arrow X while horizontally deflecting the scanning direction of
Scanning is performed by vertically deflecting the image in one direction. In this way, since the electron beam 3 scans the sample 9 from the same direction, even if the sample 9 rotates 90 degrees,
The secondary electron image obtained by the memory circuit 12 can be viewed in the same direction as the A side. Similarly, the rotary table 21
When the electron beam rotates 90 degrees in the direction of arrow a and moves to the 0 plane and the D plane, the scanning pattern rotation means 25 sequentially rotates the scanning pattern of the electron beam 3 toward the 0 plane and the D plane by 90 degrees. . Therefore, the scanning pattern of the electron beam 3 toward the 0 plane is horizontally deflected in the direction of the arrow χ and vertically deflected in the direction of the arrow Y, as shown by the arrow d shown in FIG. 3(C). .

Further, the scanning pattern of the electron beam 3 to the D plane is such that it is horizontally deflected in one direction of the arrow Y and vertically deflected in the child direction of the arrow X, as shown by the arrow e shown in FIG. 3(d). .

Therefore, in conjunction with the 90 degree rotation of the rotary table 21 of the rotation means 24, the scanning pattern rotation means 25 rotates the scanning pattern of the electron beam 3 by 90 degrees, so that the electron beam 3 is directed onto each surface of the sample 9 in the same direction. It can be scanned from.

In this way, the electron beam 3 is divided into X+, X-, Y+.

In addition to being able to scan from any of the four directions Y-, the movement of each surface A-D of the sample 9 is controlled by the rotary table 2.
1 by 90 degree rotation, and the electron beam 3
The scanning direction, that is, the scanning pattern for each surface A to D of the image plane is rotated by 90 degrees in conjunction with the rotation of the rotary table 21 by 90 degrees, so that the memory circuit 12 always records a secondary electron image in the same direction. Obtainable.

Next, the deflection waveform for scanning the electron beam 3 in four directions is shown in FIG. Period 1. After that, the electron beam 3 is scanned for a period of t2. Further, the period of the drive pulse P is set to L.

FIG. 4(a) shows the waveform of the drive pulse P. Figure 4 (bl is the A side of sample 9, the same figure (C) is the B side, the same figure (
d) shows the deflection waveform of the electron beam 3 scanned on the 0 plane, and (e) of the same figure shows the deflection waveform of the electron beam 3 scanned on the 0 plane. In this embodiment, for example, the period t of the drive pulse P is 16 m5, the hold period L1 is 8 ms, and the scan period t2 is 8 ms.

The electron beam tester for substrates of this embodiment has a rotating means 24.
The sample 9 is rotated by 90 degrees around the center of the four chamfers with the vertical axis as the rotation axis, and the scanning pattern rotation means 25 rotates the electron beam 3 in conjunction with the rotation of the rotation means by 90 degrees.
Since the scanning pattern of the sample 9 is rotated in 90 degree increments, each side of the four-sided sample 9 can be sequentially moved by simply rotating the sample 9 in 90 degree increments.
The electron beam 3 can be scanned from the same direction on each surface. Therefore, compared to the case where the table is moved in the X and Y directions, the time required to move the table is significantly shortened, and the space for moving the table is also small, making it possible to reduce the volume of the sample chamber.

In addition, in the electron beam tester for substrates of this embodiment, the scanning area of the electron beam 3 is enlarged to 66111 x 66M so that one surface of the sample 9 can be scanned at - degrees, so that the scanning area of the electron beam 3 of the sample 9 is The time can be significantly reduced.

In the electron beam tester for substrates of the above embodiment, the sample 9 was rotated by 90 degrees by the rotation means 24 with the vertical axis as the rotation axis around the center of the four chamfers.
Similar actions and effects can be obtained by rotating the electron beam scanning means 26 instead of the sample 9 by 90 degrees about an axis perpendicular to the center of the four chamfers of the sample 9 as the rotation axis.

〔Effect of the invention〕

In the electron beam tester for substrates of the first invention, the sample is rotated at 90° with a vertical axis at the center of the four chamfers as the rotation axis.
The scanning pattern rotating means rotates the scanning pattern of the electron beam by 90 degrees in conjunction with the rotation of the rotating means by 90 degrees, so that each surface of the four-sided sample can be sequentially moved. Moreover, it is possible to scan each surface of the sample from the same direction with the electron beam.

Therefore, compared to the case where the table is moved in the X and Y directions, the time required to move the table can be significantly shortened, and the space for moving the table can also be narrow, making it possible to reduce the volume of the sample chamber.

As a result, it is possible to provide a small-sized electronic beam tester for substrates that significantly shortens the inspection time.

In the electron beam tester for substrates of the second invention, instead of the sample of the first invention, the electron beam scanning means is sequentially rotated by 90 degrees with an axis perpendicular to the center of the four-sided sample as the rotation axis. , the same effects as the first invention can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 2 is a perspective view of a rotary table, FIG. 3 is a top view of a sample for explaining movement of the sample and scanning of an electron beam, and FIG. The figure shows the drive pulse waveform and the electron beam deflection waveform, Figure 5 is a block diagram showing the configuration of a conventional substrate electron beam tester, and Figure 6 shows a sample for explaining the scanning of the electron beam in Figure 5. FIG. 3... Electron beam, 4... Secondary electron, 9... Sample, 15... Sample chamber, 24... Rotating means, 25...
Scanning pattern rotation means, 26...electron beam scanning means

Claims (2)

[Claims] (1) In a reduced pressure sample chamber, each side of a four-sided sample is sequentially irradiated with an electron beam while scanning with an electron beam scanning means, and the secondary electrons emitted from the sample are detected to observe the sample. In the electronic beam tester for substrates,
A rotation means for rotating the sample in 90 degree increments about a vertical axis at the center of the four chamfers is provided, and a scanning pattern rotation means for rotating the scanning pattern in 90 degree increments in conjunction with the 90 degree rotation. An electron beam tester for substrates characterized by: (2) In a reduced pressure sample chamber, each side of a four-sided sample is sequentially irradiated with an electron beam while being scanned by an electron beam scanning means, and the secondary electrons emitted from the sample are detected to observe the sample. In the electronic beam tester for substrates,
A rotation means for rotating the electron beam scanning means in 90 degree increments about a vertical axis is provided at the center of the four chamfers, and the scanning pattern is rotated by 90 degrees in conjunction with the 90 degree increments.
An electron beam tester for substrates, characterized in that it is provided with a scanning pattern rotation means that rotates the scanning pattern in degrees.