JPH11242071A - Charged particle beam test device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable accurate defect analysis, by simultaneously irradiating a charged particle beam to two device under test(DUT) and comparing the measured result of both DUT's. SOLUTION: Charged particles (electronic beam or ion beam) are simultaneously irradiated to two DUT's 1, 2 to obtain measured data of both DUT's and their measured result is compared to perform analysis on defect or characteristic analysis. In other words, the mirror barrel parts 50a, 50b and the mirror barrel parts 60a, 60b of two systems are provided, and a stage 30c and a signal processing part 70c corresponding thereto are provided. Analysis on defect or characteristic analysis of DUT 2 is performed by using defective or unknown DUT 2 and standard DUT 1 for reference. As a result, a number of waiting times alternately moving the stage 30c is lot needed as shown in the conventional, and an analysis working time can be shortened. Furthermore, since simultaneously measured data are obtained, scattering between both the measured data is reduced, and correlative data can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charged particle beam test apparatus for irradiating a chip under test with a charged particle beam and analyzing the operation of an internal circuit. In particular, the present invention relates to a charged particle beam test apparatus that performs quality analysis and characteristic analysis by comparing non-defective devices and devices under test.

[0002]

2. Description of the Related Art A charged particle beam test apparatus is used for internal diagnosis of a device under test (DUT) placed in a vacuum.
Irradiate the T internal wiring with a charged particle beam, for example, a charged particle beam such as an electron beam or ion beam, and measure the voltage of the circuit in a non-contact manner from the amount of energy of secondary electrons generated corresponding to the potential at that site Test equipment.

A description will be given with reference to a conceptual diagram of a charged particle beam test apparatus shown in FIG. Here, a case where an electron beam is used as a charged particle beam will be described. As shown in FIG. 2, the main device configuration includes an LSI tester 200 and a test head 25.
0, stage 30, stage control unit 40, lens barrel control unit 50, lens barrel unit 60, signal processing unit 70, control C
PU90. Elements not related to the invention such as a vacuum exhaust system are not shown.

The LSI tester 200 includes a test head 25
This is a semiconductor test apparatus capable of repeatedly applying a desired test pattern 210 to a DUT via pin electronics of 0. In the case of the LSI tester 200, analysis such as pass / fail determination can be simultaneously performed upon receiving an output signal from the DUT.

The test head 250 receives a test pattern 210 at a predetermined timing from the LSI tester 200 and applies a voltage signal 260 at a predetermined amplitude and a predetermined timing to each pin of the DUT, and an output signal from the DUT. A pin electronics circuit including a comparator system for receiving timing and comparing at a predetermined timing, a switching system for measuring voltage and current, and a means for supplying power to a power supply pin of the DUT. In the case where it is not necessary to judge the acceptability by receiving the output signal from the DUT, a signal generator capable of generating output signals of arbitrary voltages and timings of a general plurality of channels is used instead of the LSI tester 200 and the test head 250. May be used.

The stage 30 is located in a vacuum column,
This is a moving stage provided with biaxial movement in X and Y directions, rotation control, and the like, and moves DUT1 and DUT2 to predetermined positions where beam operation is possible. On this stage, an IC socket for mounting a DUT having IC leads is provided, or a probe card in the form of a probe pin (probe) for contacting an electrical connection pad of a predetermined chip on a wafer is provided. The stage is movably electrically connected between the connection ends of these IC sockets or probe cards and the test head 250 via a vacuum sealing structure. Normally, one DUT 1 is used as a non-defective device or a reference device, and the other DUT 2 is mounted as a device under test. Then, for each test item, a procedure is required in which the stage 30 is alternately moved to the DUT1 side and the DUT2 side, and each time an electron beam is irradiated to find a final positioning point. It takes.

The stage control section 40 receives a control signal from the control CPU 90 and controls the movement of the stage 30 as desired.

First, the lens barrel control unit 50 includes control means for an electron optical lens (condenser lens) to control the focusing of the electron beam spot and the beam spot shape to a desired state. Secondly, a scanning control means for controlling the scanning of the electron beam in the X and Y directions is provided. Further, upon receiving a trigger signal 51 for irradiation timing control from the test head 250 or the LSI tester 200, a sampling pulse signal 58 is given to a beam blanker 64,
It has a pulse, burst, or continuous electron beam 61 generation control means capable of sampling in synchronization with a test signal applied from an IC pin of the DUT. The sampling information 59 corresponding to this occurrence is sent to the signal processing unit 7.
0. The sampling information 59 is address information for memory storage in the signal processing unit 70 corresponding to the electron beam and a timing signal.

The lens barrel 60 includes an electron gun 62 in a vacuum vessel, and irradiates an electron beam 61 focused on a predetermined beam spot and accelerated to a desired portion on the surface of the DUT so as to be deflected and scan. An electron gun 62 as a component,
There are a beam blanker 64, an XY deflection unit 65, an objective lens 67, a grid 66, and a secondary electron detection unit 68. The electron gun 62 and the beam blanker 64 generate and control the electron beam 61 described above, and receive the trigger signal 51 from the LSI tester 200 to control the generation of the electron beam as desired. The X / Y deflecting unit 65 receives the deflection signal from the lens barrel control unit 50 and deflects and scans the electron beam 61 independently in the X direction and the Y direction. The secondary electron detecting means 68 and the grid 66 receive the secondary electrons generated from the electron beam 61 irradiated on the DUT, and
6, only the electrons having an energy higher than the control voltage of 6 pass through the grid 66, the secondary electrons alone are captured by the secondary electron detecting means 68, and the detection signal is converted into an electric signal by a photomultiplier via a scintillator; Alternatively, a signal obtained by integrating the detection signal is supplied to the signal processing unit 70 as measurement data 69 converted into digital data.

The signal processing section 70 receives the measurement data 69 from the secondary electron detecting means 68, performs predetermined arithmetic conversion on the measurement data 69, receives the above-mentioned sampling information 59, and sends it to a corresponding memory address. Store them sequentially. It should be noted that the types of the measurement data 69 include image data of a potential distribution obtained by scanning a predetermined section area, and waveform data for observing a timing waveform at a specific point. After the measurement is completed, the stored series of both measurement data groups is read out, the difference between the two measurement data values or the relative delay time difference between the two measurement data is compared and analyzed, and displayed on a display device or the like. Perform failure analysis or characteristic analysis. Examples of this characteristic analysis mainly include signal propagation transitions and voltage transitions.

The control CPU 90 controls the interface with the LSI tester 200 and controls other components.

[0012]

By the way, as an analysis method for specifying which circuit part is defective in a chip of a defective DUT 2 (or an unknown DUT 2) using the above-mentioned conventional configuration, a good DUT 1 as a reference is used.
There is a method of performing analysis by comparing with the defective DUT 2 using. In this analysis method, a non-defective DUT1
After setting the DUT 2 and the defective DUT 2, the measurement is performed on both DUTs sequentially and alternately over a large number of items under the same chip position, timing condition, and test condition. From the large amount of both measurement data obtained above, a difference is obtained by comparing measurement data groups under the same conditions, and a wiring pattern or the like relating to a malfunctioning operation is highlighted from the difference to be displayed at a glance.

When performing the comparative analysis method using the non-defective DUT 1, it takes time to move the stage and irradiate the electron beam to find the initial positioning point in order to perform the measurement alternately on both DUTs. In addition, the obtained measurement data varies due to the positioning accuracy, aging, and other factors. This is not particularly preferable in a charged particle beam test apparatus that requires accurate measurement. If an analysis process is performed using the measurement data including this variation, an accurate analysis result may not be obtained, and a false recognition may be displayed as a defect. This is not preferable for failure analysis, and is a practical difficulty. Furthermore, when observing the delay time at a predetermined point in the LSI, the relative timing comparison with the reference point in the LSI cannot be performed in real time because the electron beam is one channel. For this reason, it is necessary to repeatedly irradiate the electron beam onto the position between the two points and repeat the operation, and the workability is poor. In addition, the correlation between the two relative timings is also not preferable because it causes variations. In addition, since both DUTs cannot be measured at the same time, there is a disadvantage that it takes time to measure and obtain an analysis result. Furthermore, test patterns of various test conditions are sequentially given to perform a test on a large number of test items. For this purpose, a storage medium for storing a huge amount of measurement data is required. Further, since the difference is extracted after obtaining a large amount of both measurement data, there is a time delay until the determination as to whether there is a defect in the analysis site. This is disadvantageous in that it takes a lot of time especially when searching for and specifying an unknown defective portion such as a super LSI or in failure analysis of a defective DUT 2 that causes an intermittent failure. Therefore,
The problem to be solved by the present invention is to provide a charged particle beam test apparatus capable of performing more accurate failure analysis by simultaneously irradiating two DUTs with a charged particle beam and performing measurement.

[0014]

First, the present invention for solving the above-mentioned problem is characterized in that two devices under test are simultaneously irradiated with a charged particle beam (electron beam or ion beam), and measurement data of both devices is measured. A charged particle beam test apparatus characterized by comprising means for acquiring the measured values and performing failure analysis or characteristic analysis by comparing the measurement results of the two devices under test.
According to the above invention, by simultaneously irradiating the charged particle beam to the two DUTs and performing the measurement, a charged particle beam test apparatus capable of performing more accurate failure analysis can be realized.

Second, in order to solve the above-mentioned problem, in the configuration of the present invention, a defective or unknown device under test (D
In the charged particle beam test apparatus for performing failure analysis or characteristic analysis of the device under test (DUT2) using the UT2) and the reference device (DUT1), to the corresponding IC pins or electrode pads of the same chip corresponding to each of the DUT1 and DUT2. Test signal generating means (for example, an LSI) for applying test signals of the same timing or synchronized with predetermined timing conditions
A tester 200 and a test head 250), and two systems of charged particles for irradiating individual charged particle beams to be irradiated to predetermined irradiation sites to be observed in each of the DUTs 1 and 2 at the same timing or at a timing synchronized with a predetermined timing. Two-system secondary electron detecting means 68 including a line irradiating means, individually detecting and receiving secondary electrons generated from the irradiated parts of the DUT1 and DUT2, converting them into electric signals, and supplying the electric signals to the signal processing unit 70c. Receiving the measurement data 69a and 69b from the secondary electron detection means 68, sequentially storing them in the corresponding storage locations of the storage medium, reading out the stored series of both measurement data groups, and A signal processing unit 70c for comparing and analyzing the difference or the relative delay time difference between the two measurement data to perform a failure analysis or a characteristic analysis process of the device under test (DUT2). It is a charged particle beam testing apparatus according to claim comprising.

FIG. 1 shows a solution according to the present invention. Third, in order to solve the above-mentioned problem, in the configuration of the present invention, a defective or unknown device under test (DUT)
2) In a charged particle beam test apparatus for performing failure analysis or characteristic analysis of the device under test (DUT2) using the reference device (DUT1) and the same timing or synchronized with the same same IC pin or electrode pad of DUT1 and DUT2 An LSI tester 200 that applies a test signal of a predetermined timing condition and supplies a trigger signal 51 for synchronization for synchronizing with the test signal, and a test head 250;
Charged particle beam generating means (for example, electron gun 62) in a vacuum vessel
A means for focusing a charged particle beam to a predetermined beam spot by an electron optical lens; a means for deflecting and scanning the charged particle beam; and detecting secondary electrons generated by the charged particle beam irradiated on the DUT. A first lens barrel section 60a and a second lens barrel section 60b, each of which includes the respective elements of the secondary electron detection means 68, respectively.
A stage 30c which is mounted so as to be electrically connectable to the I tester 200 side and is movable in a predetermined manner in the vacuum vessel;
Upon receiving a trigger signal 51 for controlling irradiation timing from the SI tester 200 or a trigger signal from the test head 250, the first barrel unit 60a is synchronized with a test signal applied to an IC pin or an electrode pad of the DUT. And controlling the irradiation timing of the charged particle beam by the second lens barrel unit 60b, and deflecting the beam of the charged particle beam in a predetermined manner.
There is a charged particle beam test apparatus including a first lens barrel control unit 50a that controls irradiation to T1 and a second lens barrel control unit 50b that controls irradiation to DUT2.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings together with embodiments.

The present invention will be described with reference to the conceptual configuration diagram of the charged particle beam test apparatus shown in FIG. Note that the case where an electron beam is used as the charged particle beam will be described. Also, DU
The case where T is accommodated in a package and is mounted on an IC socket provided on the stage 30c will be described. As shown in FIG. 1, the main device configuration includes an LSI tester 200,
The test head 250, the stage 30c, the stage controller 40, the lens barrel controllers 50a and 50b, and the lens barrel 60
a, 60b, a signal processing unit 70c, and a control CPU 90. In the present invention, two systems of barrel control units 50a, 50
b, and barrel sections 60a and 60b, and a corresponding stage 30c and a signal processing section 70c. The device under test DUT2 using the defective or unknown device under test DUT2 and the reference device DUT1 for reference. DUT
2 is a charged particle beam test apparatus for performing failure analysis or characteristic analysis.

The two systems of barrel control units 50a and 50b are the same as the conventional system, and receive trigger signals 51 for irradiation timing control from the LSI tester 200, respectively, and
In synchronization with the test signal applied to the pin, the first lens barrel 6
The irradiation timing of the electron beam by the first lens unit 0a and the second lens barrel unit 60b is controlled so as to be synchronized, and the scanning and deflection control of the electron beam is performed as desired to irradiate the DUT1 and the DUT2 with the same timing or the desired timing relationship. The trigger signal 51 may be supplied via the test head 250 in some cases.

The two-system barrel sections 60a and 60b are also the same as the conventional one. An electron gun 62 is provided in a vacuum container, the generation of an electron beam is controlled by a beam blanker 64, and the beam spot is narrowed to a predetermined beam spot diameter by a condenser lens. The electron beam is deflected and scanned as desired, and individually irradiates the irradiated portion of the DUT. The secondary electrons generated from the irradiated part are detected by the respective secondary electron detecting means 68 and converted into digital data, and the measured data 69a and 69b are supplied to the signal processing unit 70c. Prior to the measurement, the measurement of the timing skew between the two electron beams generated by the lens barrels 60a and 60b and the calibration for correcting the sensitivity difference between the two secondary electron detection means 68 are performed in advance. Calibrate the correlation.

The signal processing section 70c includes the two barrel sections 60
The measurement data 69a and 69b simultaneously obtained from both the secondary electron detection means 68 of a and 60b are sequentially received, subjected to predetermined arithmetic conversion, and sequentially stored in the memory addresses corresponding to the sampling information 59, respectively. Thereafter, the operation is the same as in the prior art. The stored series of both measurement data groups is read out, the difference between the two measurement data values, the relative delay time difference between the two measurement data, and the like are analyzed and displayed on a display device or the like. The failure analysis and the characteristic analysis of the test device DUT2 are performed. As a result of the configuration means of the present invention, as in the conventional case, the stage 30 is moved alternately, and each time the electron beam is irradiated, a lot of waiting time for searching the positioning point is not required, and the measurement data 69a, 69b Can be obtained, the measurement execution time can be reduced to half, and as a result, the advantage that the analysis work time can be significantly reduced is obtained. In addition, since simultaneous measurement data is acquired, the relative variation between the two measurement data is reduced, so that there is an advantage that data comparison with good correlation can be performed. As a result, there is obtained an advantage that a good comparison analysis between the two DUTs can be realized.

The stage 30c includes two DUTs 1 and 2
T2 is mounted so as to be electrically connectable to the LSI tester 200 side, and can be moved as desired in the vacuum vessel by the stage control unit 40. Further, a structure for slightly moving the interval between the two DUTs 1 and 2 is also provided. However, since the distance between the two lens barrels is constant, the electron beam is deflected by the XY deflecting means 65 so as to give a desired offset, instead of the mechanism for moving the distance between the two DUTs 1 and 2. Thus, the interval between the two DUTs 1 and 2 may be minutely controlled.

[0023]

According to the present invention, the following effects can be obtained from the above description. As described above, the present invention employs a configuration including means for simultaneously irradiating the two DUTs 1 and 2 with a charged particle beam to acquire measurement data of both devices, and comparing and analyzing the two devices. A lot of waiting time for alternately moving 30 is not required, and a great advantage that analysis work time can be shortened is obtained. Further, since simultaneous measurement data is acquired, variation between both measurement data is reduced, and data with good correlation is obtained. As a result, there is an advantage that a good failure analysis can be performed.
Therefore, the technical effect of the present invention is great, and the industrial economic effect is also great.

[Brief description of the drawings]

FIG. 1 is a conceptual configuration diagram of a charged particle beam test apparatus according to the present invention.

FIG. 2 is a conceptual configuration diagram of a conventional charged particle beam test device.

[Explanation of symbols]

 DUT1 Reference device DUT2 Device under test 30, 30c Stage 40 Stage control unit 50, 50a, 50b Barrel control unit 60, 60a, 60b Barrel unit 62 Electron gun 64 Beam blanker 65 XY deflection unit 67 Objective lens 68 Secondary Electronic detection means 70, 70c Signal processing unit 90 Control CPU 200 LSI tester 250 Test head

Claims (3)

[Claims] A means for simultaneously irradiating two devices under test with a charged particle beam and acquiring measurement data of both devices is provided, and a failure analysis or characteristic analysis is performed by comparing the measurement results of both devices under test. A charged particle beam test apparatus, characterized in that: 2. A device under test (DUT2) using a device under test (DUT2) and a reference device (DUT1).
A test signal generating means for applying a test signal at the same timing to the same IC pin corresponding to each of the DUTs 1 and 2 or the electrode pads of the same chip, and a test signal generator for each of the DUTs 1 and 2 Two types of charged particle beam irradiation means for irradiating a charged particle beam to be irradiated to a predetermined irradiation site at the same timing or at a predetermined synchronous timing, and separately detecting secondary electrons generated from the irradiation site of DUT1 and DUT2 , Receiving the measured data from the secondary electron detecting means, sequentially receiving the data from the secondary electron detecting means, and sequentially going to a corresponding storage location on a storage medium. A series of both measurement data groups stored and read out are read and compared and analyzed to perform a failure analysis or a characteristic analysis process of the device under test (DUT2). A charged particle beam test apparatus comprising: a signal processing unit; 3. A device under test (DUT2) using a device under test (DUT2) and a reference device (DUT1).
A charged particle beam test apparatus for performing a failure analysis of an LSI, applying a test signal at the same timing to the same IC pin or electrode pad corresponding to DUT1 and DUT2 and supplying a trigger signal for synchronization for synchronizing with the test signal
A tester and a test head; a charged particle beam generating means in a vacuum vessel; a means for focusing the charged particle beam to a predetermined beam spot; a means capable of deflecting and scanning the charged particle beam; A first lens barrel and a second lens barrel separately provided with secondary electron detecting means for detecting secondary electrons, and two DUT1 and DUT2 electrically connected to the LSI tester side A stage that is mounted and movable in a predetermined manner, and receives a trigger signal for controlling irradiation timing from an LSI tester, and synchronizes with a test signal applied to an IC pin or an electrode pad of the DUT, and A first lens barrel control unit that controls the irradiation timing of the charged particle beam by the lens barrel unit and the second lens barrel unit, controls the deflection of the beam of the charged particle beam in a predetermined manner, and controls the irradiation of the DUT1; To DUT2 Charged particle beam testing apparatus characterized in that it comprises a second barrel control unit for controlling the irradiation, the.