JPH02183149A - Apparatus for inspecting integrated circuit - Google Patents

Abstract

PURPOSE:To upgrade inspection accuracy and reliability by providing a reliability judging means pertaining to a voltage to be measured of a measuring pad. CONSTITUTION:A carrying section 20 is provided on a diaphragm substrate 13 to separate a vacuum section 14 from an atmospheric air section 15 to place an IC 24 thereon and a measuring pad 21 is disposed being concentrated on a side surface 13b of the vacuum section of the substrate 13. Then, individual input/output pins 25 of the IC 24 are connected to the pad 21 with a signal line 26, which 26 is connected to a driver 34 through input/output wire patterns 16 and 17. Then, a beam irradiation means 11 provided within the vacuum section irradiates the pad 21 with an electron beam 23 and a secondary electron signal detection means 30 detects a secondary electron energy radiated from the pad 21 to measure voltage signals of the input/output pins 25. Besides, a reference pad 22 is provided on a surface 13b to be connected to a specified voltage applying means 35 to monitor a state of pollution of the measuring pad 21 by irradiating the reference pad 22 with the electron beam 23 at a specified time interval by a command of a pollution monitor means 60, thereby enabling judgement of a reliability of a measuring voltage.

Description

[Detailed Description of the Invention] [Summary] The present invention relates to an integrated circuit 1, and more specifically, to an apparatus for testing a semiconductor integrated circuit, in which the amount of contaminants adhering to the surface of a measurement pad is acceptable for voltage measurement. The purpose is to improve the reliability of measurement results by determining whether or not they are within the range; 1. a vacuum section, a mounting section for the integrated circuits to be tested provided on the atmospheric section side surface of a partition wall forming a part of the vacuum section, and a mounting section for the integrated circuits to be tested to be placed on the mounting section; a plurality of measurement pads connected to each of the output pins by a signal line and exposed to the inner surface of the vacuum section of the partition;
and a beam irradiation means for irradiating the measurement pad with an electron beam, and a means for detecting secondary electron energy generated from the measurement pad by the irradiation of the beam, and further provided in the vacuum part. , a beam deflection means installed in conjunction with the vacuum section, which scans the electron beam to selectively irradiate predetermined measurement pads; converts the energy value detected by the secondary electron energy detection means into a voltage of the measurement bat; and means for monitoring contamination of the measuring pad.

[Industrial Application Field] The present invention applies to all types of ICs including LSIs, that is, integrated circuits 2.
More specifically, it relates to a device that measures signal voltages at input/output pins of a semiconductor integrated circuit using an electron beam and tests whether or not there is an abnormality in the internal circuit of the integrated circuit to be tested. The present invention relates to an integrated circuit testing device equipped with means for determining the reliability of voltage values of measurement pads in such testing.

[Conventional technology]

An integrated circuit, more specifically a semiconductor integrated circuit or IC, is
A large number of human output pins are provided around the main body, and each of them operates according to a certain built-in logic.
When an IC is manufactured, it is necessary to inspect whether each input/output pin is operating according to the designed logic, and to improve the reliability of the manufactured IC.
It is common practice to perform a complete check.

However, since such tests involve a huge number of ICs to be tested, it is necessary to perform highly accurate measurements quickly in a very short period of time, and to shorten the number of man-hours required for testing and perform it with high efficiency. That is required.

Conventionally, testing of such ICs, etc., involves, for example, inserting the IC to be tested into a board having a signal input/output wiring pattern, and connecting the input/output pins or leads of the IC to be tested to the wiring pattern. and set it in a vacuum chamber, then operate the vacuum pump to make the chamber vacuum, and then
Applying a signal to the IC to be tested via the wiring pattern,
Meanwhile, by scanning the input/output pins or leads of the IC using an electron beam generation and scanning means installed in the vacuum chamber and observing the voltage at the input/output pins or leads irradiated by the beam at that time. It was being executed.

However, in the method described above, (1) the IC is in an operating state during the test and generates heat during the test; The heat generated by the IC itself affects the test results.

If the IC is rated for high power consumption,
Especially so. Therefore, it is necessary to cool the IC, but since the IC is set in a vacuum, it is difficult to cool the IC.

■ Since the vacuum chamber is opened each time the IC to be tested is changed, it is necessary to operate the vacuum pump to evacuate the chamber after setting the new IC.
It is necessary to wait several minutes after setting C before starting the test, which requires a large number of testing steps.

■ The range in which the leads are dispersed is wider than the scanning range of the electron beam, and it is not possible to scan all the leads at once.
It is necessary to send C, etc. on an X-Y stage, which requires a large number of testing steps.

Furthermore, such conventional testing methods are unsuitable for ICs rated for particularly high power consumption, and have poor testing efficiency.

In order to solve this problem, the applicant of the present invention has proposed an IC inspection device as shown in FIG. (Refer to Japanese Patent Application No. 62-16579.) In other words, this inspection device inspects the tC on the atmospheric side 139 of the substrate 13, which functions as a partition wall separating the vacuum section 14 and the atmospheric section 15, as shown in FIG.
etc. 24 are installed, and the measurement pads 21 electrically connected to the individual input/output bins 25 of the ICs etc. through the substrate are centrally arranged on the surface 13b exposed to the vacuum part side of the substrate. The measuring pad is irradiated with an electron beam 23 by a beam irradiation means provided in the vacuum section, thereby detecting the secondary electron energy emitted from the measuring pad and converting it into a voltage by an appropriate means. The voltage signal of the input/output pin connected to the measurement pad is determined by 21t11.

In the above device, the IC is placed in the atmosphere and the signal is measured on the measurement pad, so the IC can be replaced in a short time.
■It is possible to cool the IC, ■Once you have registered the parameters necessary for pad voltage measurement using an electron beam,
It has excellent features such as no need to update parameters even if the IC is replaced.

However, even in the above device, if the measurement pad is used in a vacuum area while being irradiated with an electron beam for a long time, dirt consisting mainly of hydrocarbons will adhere to the surface of the measurement pad, and such dirt When a beam is irradiated onto a measurement pad that has attached to it, it becomes charged, and the secondary electron energy emitted from the measurement pad changes, making it possible to accurately measure the voltage at the measurement pad. It disappears. Furthermore, if the pad is heavily contaminated, it becomes impossible to measure the voltage at all, making it necessary to change the measuring pad.

Therefore, if the above test is carried out without knowing that contaminants have accumulated on the measurement pad, judgments will be made based on unreliable voltage measurements, which will reduce the reliability of the test results of semiconductor integrated circuits. The drawback was that sufficient quality control could not be carried out.

[Problem to be solved by the invention]

An object of the present invention is to improve the above-mentioned drawbacks and to provide an integrated circuit testing device capable of improving the accuracy and reliability in testing integrated circuits by providing means for determining the reliability of the measurement voltage of the measurement pad. This is what we provide.

[Means for Solving the Problems] An integrated circuit testing device according to the present invention has the following technical configuration in order to achieve the above object.

That is, a vacuum section, a mounting section for integrated circuits to be tested provided on the atmospheric section side surface of a partition forming a part of the vacuum section; i); a plurality of integrated circuits to be tested placed on the mounting section; a plurality of measurement pads connected to each of the individual output pins by signal lines and exposed to the inner surface of the vacuum section of the bulkhead; A beam irradiation means for irradiating an electron beam and a means for detecting secondary electron energy generated from a measuring pad by the irradiation of the beam are provided.Furthermore, a means for detecting the energy of secondary electrons generated from a measurement pad by the irradiation of the beam is provided. An integrated circuit provided with a beam deflection means for selectively irradiating the measurement pad, a means for converting the energy value detected by the secondary electron energy detection means into a voltage on the measurement pad, and a measurement pad contamination monitoring means. This is an inspection device.

That is, the integrated circuit testing device of the present invention, more specifically, the semiconductor integrated circuit testing device improves testing accuracy when testing ICs including LSIs, that is, semiconductor integrated circuits using the previously proposed testing device described above. Streamline the required scans and
In addition to increasing the efficiency, the reliability of voltage measurement can be determined by providing means for monitoring contamination of the measurement pad. In other words, the purpose is to improve the reliability of the test results by configuring the system so that it is possible to detect contamination of the measurement pad at an early stage and perform the necessary processing to eliminate the contamination. It is something to do.

The contamination monitor used in the present invention detects the amount of contaminants, mainly hydrocarbons, etc. that adhere to the surface of the measurement pad, and the amount of contaminants that adhere to the surface of the measurement pad determines the reliability when measuring the pad voltage. This is to determine whether a certain signal value is within a range of allowable values. If it is within this tolerance range, it is determined that the measurement pad is not yet completely contaminated and that a highly reliable measurement voltage can be obtained. Such a monitor may be of any type, whether direct or indirect, or using electrical, optical, or mechanical methods, as long as it has the above-mentioned functions. As an example of such a monitoring means, one having a component structure and high resolution is used, and a reference pad is provided separately from the measurement pad.

In this case, the reference pads are made of the same material as the measurement pad, and are arranged in an appropriate number near the measurement pad. It is configured so that it is not connected to any of the input/output bins of the semiconductor integrated circuit for inspection, and a separately specified voltage is applied thereto.

In such a configuration, in order to determine the reliability of voltage measurement, first, while testing a semiconductor integrated circuit such as an IC,
When a predetermined time comes, a specified voltage is applied to the reference pad, and the electron beam is deflected to the reference pad to irradiate the reference pad and measure the actual voltage of the reference pad.

In addition to the normal deflection operation of the measurement pad, such electron beam deflection is achieved by registering the position data of several reference pads in advance in a table forming a predetermined memory, and using that data at a predetermined time. This is done by operating a deflection coil driver that controls the deflection coil via the reference pad polarization control means.

In the present invention, the measurement pad can be used as a means for measuring the voltage in the reference bat, but is not limited in any way, but as an example, the following method may be used. That is, by utilizing the fact that the secondary electron energy generated when an electron beam is irradiated onto a measurement pad mainly made of metal changes depending on the potential given to the metal in advance, an appropriate energy analysis means can be used in a vacuum chamber. , and converts the intensity of the detected secondary electron energy into a change in the intensity of the secondary electron signal, and further converts this into a voltage. The analysis means consists of a secondary electron energy detection means and a mesh filter to which a voltage can be applied, and as shown in FIG. 5, the voltage applied to the mesh filter (analysis voltage) Vr is varied. When a known voltage (sample voltage) (e.g. -2V) is applied to a predetermined input/output bin of the IC to be tested, etc., the signal of secondary electrons emitted from the measurement pad is thereby The intensity T is the S curve of Sl (
Similarly, a known voltage (sample voltage) V2 (e.g. OV) higher than ■1 is applied to the same input and output bins.
! Obtain the S curve of

At this time, if a reference level sth as a threshold value is set to an appropriate value between the maximum and minimum values of the secondary electron signal intensity value T, the intersection Vr2. It is known that the difference from Vrl (Vrz Vr+) is approximately equal to the sample voltage difference (Vz - V+), so when testing a pad whose sample voltage is unknown behind the measurement pad, the decomposition voltage Vr By repeatedly measuring the feedback while measuring the secondary electron signal strength T by changing the voltage appropriately, the analysis voltage Vr is obtained when a lower secondary electron signal strength value that matches the reference level sth is finally obtained. , and the sample voltage of the measurement pad.

In the present invention, an appropriate number of reference pads are arranged near the area where the measurement pads are arranged, and the number is not particularly limited, but can be increased or decreased in proportion to the number of measurement pads used. Ru.

It is also preferable that the electron beam be placed at a position where scanning with the electron beam can be performed efficiently.

The predetermined specified voltage for the reference pad may be any voltage value, but it is desirable to set it to a voltage value that is approximately the same as the voltage value applied to the input/output bin of the semiconductor integrated circuit under test.

In addition, when talking about the time (timing) or frequency of irradiating the reference pad with the electron beam when performing contamination monitoring, basically the contamination is proportional to the number of times the measurement pad is irradiated with the electron beam. Since material is expected to be deposited, it should be considered that the beam irradiation dose (proportional to the number of irradiations) on the measurement pad and the beam irradiation dose on the reference pad are substantially equal. Therefore, when beam irradiation for voltage measurement is performed on each of a set of measurement pads corresponding to a certain number of input/output bins made up of one logic, beam irradiation is also performed on the reference pad located near it. must be programmed to occur. For example, if one logic circuit is configured with two human output pins and one output pin, beam irradiation is performed once on the measurement pad corresponding to each human output pin, and each measurement voltage is is recorded, and then the reference pad is irradiated with a beam once. Usually, one input/output pin in a semiconductor integrated circuit is often incorporated into other logic, so there are many measurement pads corresponding to the output pin, which is exposed to beam irradiation many times compared to the number of logic tests. Therefore, the frequency of beam irradiation to the reference pad does not necessarily match the number of inspections for each logic.

In that case, it is preferable to constantly calculate the average value of the number of times the measurement pad is irradiated and irradiate the reference pad with the beam in accordance with the average value. By doing so, it is possible to substantially balance the amount of contaminants attached to the reference pad and the amount of contaminants attached to the measurement pad, thereby improving measurement accuracy and reliability.

Therefore, in the present invention, the timing of irradiating the reference pad with the electron beam is determined based on the number of measurements as described above, and this can be executed by appropriate program operations.

Next, in the present invention, based on the above, the degree of contamination on the reference pad is monitored using a monitoring means during the IC test, and the monitoring is performed after a predetermined number of tests has elapsed. It is only necessary to provide a necessary program control means for the monitoring means. Taking the case where the reference pad is used as the monitoring means as an example, when it is necessary to judge the contamination state, the command from the monitoring means is sent. A specified voltage is applied to the reference pad, and at the same time, the reference pad is irradiated with an electron beam by a deflection coil driver, and the pad voltage at that time is measured, for example, by the method described above.

Thereafter, the specified voltage value and the measured voltage value are compared. As a comparison method, known comparison means such as ratio, deviation, etc. may be employed.

Next, compare the comparison value obtained in this way with the predetermined standard value for which the degree of contamination is acceptable, and if the degree of contamination is within the acceptable conditions, resume normal inspection, It determines that the measuring pad has reached the end of its life and displays an alarm.

Although this is out of the scope of the present invention, in the present invention, when the above alarm occurs, the measuring pad is replaced, and the contaminants attached to the measuring pad are automatically removed on-machine or chemically in a separate process. Alternatively, a mechanical removal process can be performed.

[For production]

Since the present invention is an inspection device having the above-mentioned configuration, by mounting an IC, etc., which is an object to be inspected, in a non-vacuum section, cooling of tC, etc. is facilitated, and it is possible to cool down the tC etc. without destroying the vacuum section. It can be replaced with other ICs, etc.

Since the group of monitoring pads scanned by the electron beam are arranged in a concentrated manner, the above scanning is completed at once. In addition, in the present invention, since the contamination state of the measurement pad is constantly monitored, a contaminated measurement pad can be detected early and replaced or reprocessed. The reliability of the test can be greatly improved, contributing to faster and more efficient testing of semiconductor integrated circuits.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing a specific example of a semiconductor integrated circuit testing apparatus used in the present invention. That is, the basic structure of the inspection apparatus of the present invention is as shown in FIG. IC etc.24
A mounting section 20 is provided on which the IC, etc. is placed, and the input/output pins of the IC, etc. 24 are inserted and placed thereon. A measurement pad 21 made of a highly conductive metal such as copper is electrically connected to each input/output bin 25 of this IC, etc. via an arbitrary signal line 26 via the substrate 13, and is placed on the vacuum side of the substrate. The input/output bins 25 are connected to the measurement pad 21 by irradiating the measurement pad 21 with an electron beam 23 by the beam irradiation means 11 provided in the vacuum section. It measures the voltage signal of

The signal line 26 connecting the measurement pad 21 and each input/output bin of the semiconductor integrated circuit 24 has an input/output wiring pattern (16, 17) connected to an appropriate semiconductor integrated circuit driving device 34 in the substrate 13. It is connected. When measuring the voltage of the measurement pad, the I
Since non-tested semiconductor integrated circuits such as ICs need to be measured under the same conditions under which they operate under actual usage conditions, they are put into a driving state via the control unit 34. Specifically, ICs, etc. The input pin 25 of the semiconductor integrated circuit is connected to the drive device 34 .

The beam irradiation means 11 is usually an electron gun, and the electron beam 2 emitted from the beam irradiation means is
3 is appropriately focused by an electron lens 40 as shown in FIG. 1, and then the direction of the beam is scanned by a deflection coil 41 to irradiate the beam onto a predetermined measurement pad.

Such a deflection operation specifies the position of the measurement pad using X-Y coordinate values, etc., stores it in the control means that controls the deflection coil driver etc. 42 via the input device 46, and irradiates the beam onto the specific measurement pad. When desired, the address of the measurement pad is accessed and its X-Y coordinate data is read out, thereby controlling the deflection coil driver 42 to direct the beam 23 to the selected measurement pad.

Next, in the present invention, as described above, the secondary electron signal detection means 30 detects the secondary electron energy emitted from the measurement pad and converts the intensity value into the electric signal T.
is provided in the vacuum chamber 10 near the measurement pad 21.

Furthermore, the secondary electron signal strength detection means has as a part an energy filter means to which a voltage can be applied for controlling the path of the secondary electrons. The filter means is an analysis voltage generation circuit attached to the vacuum chamber! 32, a transport analysis voltage value is applied, and the detection signal from the secondary electron signal strength detection means 30 is processed by a secondary electron signal detection circuit 33 and converted into a secondary electron signal value T. , and is converted into a voltage by the pad voltage measuring means 49 and stored in the parameter table 43.

Next, in this embodiment, the reference pad 22 is used as a part of the contamination monitoring means 60 that monitors the contamination status of the measurement pad. The reference pad 22 is provided on the vacuum section side surface 13b of the same substrate as the measurement pad, and an example of its arrangement form and number is shown in FIG. 3 together with an example of the arrangement of the measurement pad.

The reference pad is not connected to an input/output bin such as an IC, but is connected to a specified voltage applying means 35, and a specified voltage is applied at predetermined time intervals according to a command from the contamination monitoring means.

On the other hand, while the designated voltage is applied to the reference pad, the electron beam emitted from the electron beam irradiation means 11 is operated by the deflection coil driver 42 in response to a command from the reference pad beam deflection control section 61 to provide necessary reference. It irradiates the pad.

In this operation, the position of each reference pad 22 is input in advance as X-Y coordinate data from the input device 46 and stored in the table 43 of the pad voltage measuring means 49, and the data is used as a command to the contamination monitoring means 60. The control unit 61 reads the information and performs beam irradiation.

As mentioned above, the time frequency of beam irradiation to the reference pad is programmed using the data in the parameter table registered in the contamination monitoring means so that the amount of electron beam irradiation to the reference pad and the measurement pad is approximately equal. configured to process and determine. That is, irradiation of the reference pad with an electron beam (i.e.,
If the frequency of electron beam irradiation (i.e., measurement) on the measurement pad is different, the amount of dirt generated on the pad will be different, which may lead to incorrect judgment (especially if the frequency of judgment is higher than the frequency of the measurement). (This becomes a problem if the number is small.) So, for example,
Assuming that the number of determination pads required for testing one IC is N, determination is made every time measurement is performed N times.

At this time, which measurement pad is inspected and which reference pad is irradiated is also determined by the contamination monitoring means in consideration of scanning efficiency.

When it is time to perform contamination monitoring, the pad voltage measuring means that measures the voltage of the measurement pad through the normal route is stopped by a command from the contamination monitoring means, and no external measurement requests are accepted. After setting the state,
A specified voltage Vre is applied to a predetermined selected reference pad. Next, the contamination monitoring means 60 causes the reference pad beam deflection controller 6 to measure the pad voltage of the reference pad.
1 and a command to the pad voltage measuring means 49 to irradiate the reference pad with the electron beam 23 and to excite the analysis voltage generating means to activate the filter means of the secondary electron energy detecting means and its detection circuit. A measured voltage V rp-s is obtained from the secondary electron energy and stored in the parameter table 43 .

Next, from the above two voltage values, for example, the absolute value of the deviation (V
r, V (r, m)) and compares it with a predetermined tolerance value, l Vrp
If -V (r, -m) l > permissible value, it is determined that the measuring pad has reached the end of its service life, and an alarm 1 is generated to display a message requesting replacement of the measuring pad.

The contamination monitoring execution means for determining the degree of reliability of the measured voltage in the present invention will be explained below with reference to the flowchart of FIG.

Assume that at the start, the value of the test number counter (measurement counter) L provided in the contamination monitoring means 60 is Li. (Step a) If the counter value is not the predetermined number of inspections N (Step b), a measurement request instruction for the measurement pad is issued (Step g
) According to the instruction, the voltage of the predetermined measuring pad/node is measured (step h), and the counter (shi) is incremented (L±1) (step i).

Next, when it is determined that the test of the semiconductor integrated circuit (Iq) to be tested has been completed (step j), the counter value at that time is saved (step k).

On the other hand, if L=N in step b, specified voltages V and r are applied to a predetermined reference pad (step C), and then the voltage V (r, -m) of the reference pad is measured (
Step d).

Next, the difference between Vpr and V (rl, -m) V (r,
m) -Vrpl is calculated and if the result is not greater than the tolerance value (step e), the counter value is reset to 0 (step f) and the testing of the measuring pad is restarted. On the other hand, if the value exceeds the allowable value in step e, a message indicating deterioration of the measuring pad is displayed on the display device (step r') and the testing of the measuring pad is completed.

〔Effect of the invention〕

According to the present invention, since the IC, etc. to be inspected is mounted in a non-vacuum area rather than a vacuum area, it is easy to cool the IC, etc., and even if the IC etc. easily generates heat, it can be easily cooled down during the inspection. It is possible to prevent heat generation from ICs, etc., and to obtain accurate test results without the influence of heat.

Furthermore, since ICs and the like are mounted in the non-vacuum section, the vacuum state can be maintained in the vacuum section even after the inspection of the negative IC, etc. is completed, and by removing it and mounting the next IC, etc. Therefore, there is no need to operate the vacuum pump to create a vacuum every time an IC, etc. is installed. However, after removing the - IC, etc. and installing another TC, etc., the inspection of this IC, etc. can be started immediately. I can do it. In other words, a plurality of ICs etc. can be tested continuously.

In addition, since the measurement pads are concentrated in one place, the electron beam can scan all the monitor pads at once without changing the position of the electron gun, etc.
It is possible to shorten the time required for testing ICs, etc.

'Furthermore, in the present invention, since the contamination state of the measuring pad is constantly monitored, a contaminated measuring pad can be detected early and replaced or reprocessed. This avoids giving incorrect test results without knowing about pad deterioration, etc.
This not only improves the reliability of test results for ICs and the like, but also contributes to faster and more efficient testing of semiconductor integrated circuits.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing an apparatus for testing a semiconductor integrated circuit according to the present invention. FIG. 2 is a basic structural diagram of a semiconductor integrated circuit scanning device according to the present invention. FIG. 3 is a diagram showing an example of the arrangement of measurement pads and reference pads in the present invention. FIG. 4 is an execution flowchart of the contamination monitor according to the present invention. FIG. 5 is a diagram showing one method of measuring the voltage of the measurement pad used in the present invention. 10... Vacuum chamber, 11... Electron beam irradiation means, 12... Vacuum pump, 13... Substrate, 14...
・Vacuum part, 15... Atmospheric part, 16... Wiring pattern for signal input, 17... Wiring pattern for signal output, 20... Semiconductor integrated circuit mounting part, 13a... Atmospheric part of substrate Side surface, 13b... Vacuum part side surface of substrate, 21... Measurement pad, 22... Reference pad, 23... Beam, 24,
24', 24''...Semiconductor integrated circuit to be tested, 25
...Input/output pin, 26...Signal line, 30...Secondary electron energy detection means, 32...Analysis voltage generation circuit, 33...Secondary electron detection circuit, 34...Semiconductor integrated Circuit driving device, 35... Designated voltage application means, 40... Electronic lens, 41... Deflection coil, 4
2... Deflection coil driver 43... Parameter table, 45... Measurement result output device, 46... Human power device, 49... Pad voltage measuring means, 60... Contamination monitoring means, 61. ...Reference pad beam deflection control section. Figure 2 + 3b O: Measuring pad (21) l: Reference pad (22) Figure 9 showing an example of the arrangement of measurement pads and reference pads Figure 9 shows the principle of how to measure the voltage

Claims (1)

[Scope of Claims] 1. A vacuum section, a mounting section for an integrated circuit to be tested provided on the atmospheric section side surface of a partition wall forming a part of the vacuum section, and a test object placed on the mounting section. a plurality of measurement pads connected to each of the plurality of input/output pins of the integrated circuit for use by signal lines and exposed to the inner surface of the vacuum section of the partition;
and a beam irradiation means for irradiating the measurement pad with an electron beam, and a means for detecting secondary electron energy generated from the measurement pad by the irradiation of the beam, and further provided in the vacuum section. , a beam deflection means installed in conjunction with the vacuum section, which scans the electron beam to selectively irradiate a predetermined measurement pad, and converts the energy value detected by the secondary electron energy detection means into the voltage of the measurement pad. 1. An integrated circuit testing device comprising means for converting and means for monitoring contamination of a measurement pad. 2. The contamination monitor includes means for supplying a reference voltage signal, and the means for supplying the reference voltage signal is not connected to any of the input/output pins of the integrated circuit under test, so that only a specified voltage is applied. 2. The testing device of claim 1, wherein at least one reference pad is provided adjacent to said measuring pad. 3. The contamination monitoring means includes means for comparing a specified voltage applied to the reference pad with a measured voltage obtained from the reference pad, and means for comparing the comparison result obtained by the comparison means with a predetermined standard. The inspection device according to claim 2, characterized in that it is comprised of: