JPH0356864A - Electron beam device - Google Patents

Abstract

PURPOSE:To measure a sample voltage waveform at high-speed by finding the sample voltage referencing S curve showing the relation between an analytical voltage stored into the memory and a secondary electronic signal, from a secondary electronic signal obtained with a phase scanning of an electron beam pulse. CONSTITUTION:With the instruction from a control computer 32 the phase phiof a phase control circuit 26 is set to phio, in this state the analytical voltage Vr is scanned like Vro-Vra. The relation between this voltage Vr and the mea sured secondary electronic signal S is stored to the memory in a voltage measur ing circuit 30 as the S curve Co. The S curve Co is inputted into the computer 32, and the computer 32 sets the analytical voltage Vri based on the Co so as to the secondary electronic signal S becomes a slice level Sl. With the instruc tion of the computer 32 the analytical voltage Vr is made to Vri, in this state the phase phi of the electron beam pulse 18 is scanned like phio-phin, the obtaining secondary electronic signal S is inputted to the circuit 30, the S curve Co stored to the memory is referred to, and the sample voltage Vs is found.

Description

[Detailed Description of the Invention] [Summary] Regarding the electron beam device, by not scanning the analysis voltage, the sample voltage waveform can be measured at high speed, and furthermore, by not applying a known voltage to the sample, the applicable range can be expanded. Aiming to provide a wide range of electron beam devices, the present invention includes an analysis voltage power source that provides a sample analysis voltage, a means for irradiating an electron beam pulse to a measurement location on a sample, and a phase control circuit that controls the phase of the electron beam pulse. An electron beam apparatus comprising: a detector for detecting a secondary electron signal emitted from a measurement location of a sample; and a voltage measurement circuit for determining a sample voltage based on the secondary electron signal from the detector. , S which shows the relationship between the analysis voltage and the secondary electron signal by scanning the analysis voltage in a certain phase.
The voltage measurement circuit includes a memory for storing a curve, and an analysis voltage is set from the S curve stored in the memory, and the voltage measurement circuit detects a secondary electron signal obtained by phase scanning of an electron beam pulse at the time of the setting and analysis voltage. The sample voltage is determined by referring to the S curve stored in the memory.

[Industrial application field]

The present invention relates to an electron beam device.

Electron beam equipment is used as a device for analyzing the operation of high-speed LSIs and diagnosing defects. In this electron beam equipment, electron beam pulses are irradiated onto the LSI, etc. as a sample, and the electron beam pulses emitted from the sample are detected. The sample voltage is determined based on the secondary electron signal. Since the LSI screens to be measured are becoming larger in scale, it is necessary to analyze and diagnose them quickly. In such analysis and diagnosis, it is often desired to obtain sample voltage information regarding the phase rather than accurately obtaining the sample voltage. Therefore, rather than spending a long time to accurately determine the voltage waveform of the sample voltage, it is desired to quickly determine the logical waveform of the sample voltage.

[Conventional technology]

FIG. 5 shows a conventional sample voltage measurement method using an electron beam device.

In FIG. 5, the analysis voltage vI is determined so that the secondary electron signal (S) becomes the slice level S,1 (-2, 0,
2) Set these analysis voltages (-2, 012) to the sample voltage ■
It is said that That is, the sample S voltage V is -2V, OV, and +2V, respectively.

Next, FIG. 6 shows another conventional sample voltage measurement method using an electron beam device.

In FIG. 6(A), the relationship between the analysis voltage V and the secondary electron signal S is shown, and the secondary electron signal ss, S, when the analysis voltage V is 1r is calculated by rO
-21 0 count.

On the other hand, the analytical voltage ■ is V,. The correspondence between the sample voltage ■ and the quadratic quintuplet S signal S as shown in Fig. 6f(B) is prepared in advance, and this
Based on the correspondence relationship of B), the secondary electronic signal s,, SoS
Find the sample voltage V, corresponding to S+2. That is, the sample voltages (2) are S -2V, OV, and +2V, respectively.

[Problem to be solved by the invention]

In the measurement method shown in FIG. 5 above, since the analysis voltage V must be scanned, the secondary electron signal S must be measured many times, making high-speed measurement difficult. Furthermore, even if the response of the analysis grid is taken into consideration, there is a limit to speeding up.

In the measurement method shown in Fig. 6 above, it is necessary to prepare in advance the correspondence between the sample 1 pressure V and the secondary electron signal S, as shown in Fig. 6 (B). The correspondence relationship in (B) is when the analysis voltages are set to ■, V, and 0. Therefore, if a known voltage cannot be applied to test f', this measurement method cannot be used, and its range of applicability is narrow.

An object of the present invention is to provide an electron beam device that can measure sample voltage waveforms at high speed and has a wide range of applications.

[Means to solve the problem]

The present invention provides an analysis voltage power source 20 for providing an analysis voltage V of the analyzer 9, a means 10 for irradiating an electron beam pulse 18 onto a measurement location 16 of a sample 14, and a means for controlling the phase of the electron beam pulse 18. φ0 to φ. a phase control circuit 26; a detector 28 for detecting the secondary electron signal S emitted from the measurement location 16 of the sample 14; and the detector 2.
In an electron beam apparatus including a voltage measurement circuit 30, which calculates a sample voltage ■ based on a secondary electron signal S from
Scanning the analysis voltage V,0~■ at a certain phase φ0, the function III of the analysis voltage V and the secondary electron signal S
S curve C showing the 1st section.

The analysis voltage V 1 is set from the S curve Co stored in the memory, and the voltage measurement circuit 30 includes a memory for storing the analysis voltage V . At the same time, the phase scanning φ of the electron beam pulse t8■. From the secondary electron signal S obtained by ~φ, with reference to the S curve co stored in the memory,
Configure S to find the sample voltage.

[Effect]

FIG. 1 shows a sample voltage measurement method according to the principle of the present invention, and FIG. 1(A) shows the relationship between the phase φ of the electron beam pulse and the sample voltage V, and FIG. B) shows the relationship between the analysis voltage V and the secondary electron signal S. And Fig. l (B
), the S curve Co has the phase φ in FIG. 1(A).
(sample voltage V,.), and the S curve Ci is the phase φ (
It corresponds to the sample voltage vsQ+ΔvS).

First, the phase of the electron beam pulse is set to φ = φ, the sample 0 voltage V = V, o, the analysis voltage V is scanned, S (Vs. ~ V, I1), and the secondary electron signal S is measured.
An Sr curve Co showing the relationship between the analysis voltage V and the secondary electron signal S is obtained. Next, the phase of the electron beam pulse φ = φ, the sample voltage V = V, + Δ■, and l
s and measure the secondary electron signal S, an S curve CI is obtained. Since this S curve C is a state in which the S curve Co1 is shifted to the right by ΔV, the analysis voltage V corresponding to the secondary electron signal S, for example, the slice level S, has a phase φ. When the phase is φl, it is vLl, and when the r phase is φl, it is v,1+Δvs. In this way, S
By measuring the shift amount of the curve, the sample voltage V
The displacement of can be found.

t Therefore, the analysis voltage V is set to V and the secondary voltage r
Considering the case where the τ child signal is measured, the secondary electron signal is S at the phase φ, and O at the phase φ1.
When sl, the S curve shifts to the right by Δ■, and the secondary electron signal is Ss1-ΔS. by the way,
The analysis voltage at which this secondary electron signal S, -ΔS is obtained at phase φ0 is ■ -ΔV, which is
S is shifted to the left by Δ■ from the intersection S1 between the secondary electron signal S-ΔS and the S curve C1.

S Therefore, if the S curve Co is known, the S curve Cl
The shift amount AV is determined from the intersection of the analysis voltage and the analysis voltage. Here, since V and o are known S, the sample voltage ■So+ΔV is found.

Based on the above principle, the present invention operates as follows.

First, the analysis voltage V, is scanned at a certain phase φ0 (■
1,~■,. ), analysis voltage (■), and secondary electron signal S, an S-curve Co is determined, and this S-curve Co is stored in a memory. Next, the S curve Co stored in memory is
The analysis voltage ■, is set from , and the secondary electron signal S, (from −ΔS,
With reference to the S curve Co stored in the memory, the sample voltage V, o+Δ■, is determined.

〔Example〕

Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 2 shows a circuit of an electron beam device according to an embodiment of the invention.

In FIG. 2, an EB (electronic beef) lens barrel 10 serving as an irradiation means includes a deflector 12 therein, and an electron beam pulse 18 deflected by the deflector 12 is irradiated onto a measurement location 16 of a sample 14. be done. Incidentally, the analyzer 19 is supplied with an analysis voltage (2) from an analysis voltage power supply 20.

r code 22 is the L S that drives the LSI as the sample 14;
The clock signal 24 from the I drive circuit 22 is supplied to a phase control circuit 26. This phase control circuit 26 synchronizes with the operation of the LSI drive circuit 22.
The irradiation means 12 generate electron beam pulses 18.

Secondary electron signal S emitted from measurement point 16 of sample 14
is detected by the detector 28 and supplied to the voltage measuring circuit 30. This voltage measurement circuit 30 has an S curve C. and sample voltage (■), and obtain the S curve C. and sample voltage ■,
is supplied to the control computer 32. In addition, the voltage measurement circuit 3
0 has a memory (not shown) therein for storing the determined S-curve Co.

Further, the control computer 32 controls the analysis voltage power supply 20, the phase control circuit 26, and the voltage measurement circuit 30.

The electron beam device according to the embodiment of the present invention has the above-mentioned structure, and its operation will be explained below with reference to FIGS. 3(A) and 3(B).

First, FIG. 3(A) shows the operation during measurement preparation. In FIG. 3(A), the phase control circuit 26 has its phase φ set to φ0 according to an instruction from the control computer 32, and in this state, the analysis voltage V is set to v,o~■+
scanned like n. The relationship between the scanned analytical voltage (■) of f and the secondary electron signal S measured at this time is S curve C. and stored in the memory within the voltage measurement circuit 30.

This S carp C. is supplied to the control computer 32, and the control computer 32 sets the analysis voltage (2) such that the secondary electron signal S becomes the slice level Ssl based on the S curve CO. This analysis voltage ``■'' is a set analysis voltage at the time of measurement, which will be described later.

r Next, FIG. 3(B) shows the operation during measurement. In FIG. 3(B), according to instructions from the control computer 32, the analysis voltage V is changed to the above-mentioned setting. In this state, the phase φ of the electron beam r pulse 18 is φ0 to φ. is scanned like this. When the secondary electron signal S obtained in this way is input to the voltage measuring circuit 30, the voltage measuring circuit 30 refers to the S curve co stored in the memory and determines the sample voltage
, can be found.

The procedure for determining this sample voltage (2) will be explained using FIG. 1 (B). Set analysis voltage V. At times, r
l When the secondary electron signal S is S - ΔS, the S curve C stored in the memory. The shift amount Δ■ is determined by referring to

Then, the sample voltage v+0+Δ■ is obtained.

Next, FIG. 4 shows an example of measurement using an electron beam device. Incidentally, in FIG. 4, the apparatus shown in FIG. 2 has been slightly modified, and output logic waveforms are shown.

In addition, when the amplitude of the sample pulse is expected to be V, after determining the analysis voltage ■,S such that the secondary electron signal S becomes S at the time of registration, that is, during measurement preparation, ■±1/ Secondary voltage It corresponding to 2V
Find the p child signal S ±ΔS from the S curve. Measurement I
p Sometimes, S = ΔS - ΔS, S = S lhl + l p th2 ++
If ΔS is larger than p secondary electronic signal S 75<S input to the voltage measurement circuit 30, -1
and if it is smaller than h2 S, it is +1, and S ≦S≦lhl
O if iblS
shall be. By ternarizing in this way, the logical waveform can be measured even if it is not known whether the level at phase 0 is L level or H level.

[Effects of the Invention] As explained above, according to the present invention, since the analysis voltage is not scanned, the sample voltage waveform can be measured at high speed.Furthermore, since no known voltage is applied to the sample, the applicable range is widened. It has the advantage of being spacious.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the principle of the present invention, Fig. 2 is a circuit diagram of an electron beam device according to an embodiment of the present invention, Fig. 3 is an explanatory diagram of the operation of the electron beam device of Fig. 2, and Fig. 4 is an electron beam FIG. 5 is an explanatory diagram showing a conventional sample voltage measuring method, and FIG. 6 is an explanatory diagram showing another conventional sample voltage measuring method. 10...EB lens barrel 12...Deflector 14...Sample 16...Measurement point 18...Electron beam pulse 19...Analyzer 20...Analysis voltage power supply 22...LSI drive Circuit 24... Clock signal 26... Phase control circuit 28... Detector 20 - Voltage measurement circuit 32... Control computer φ... Phase of electron beam pulse ■ - Sample voltage 5 ■... Analysis voltage f S...・Secondary electron signal C o 1C l"' S curve

Claims (1)

[Claims] An analysis voltage power supply (20) that provides an analysis voltage (V_r) of an analyzer (19), and means for irradiating an electron beam pulse (18) to a measurement location (16) of a sample (14). (10)
and the phase of the electron beam pulse (18) is controlled (φ
_0~φ_1) Phase control circuit (26) and sample (14)
Secondary electron signal (S) emitted from the measurement point (16)
a detector (28) that detects the
The sample voltage (V_s
), and an electron beam device that scans the analysis voltage (V_r_0) at a certain phase (φ_0).
0 to V_r_n) and stores an S curve (C_0) showing the relationship between the analysis voltage (V_r) and the secondary electron signal (S).
), the analysis voltage (V_r_i) is set, and the voltage measuring circuit (30)
Sometimes, the phase scanning (φ_0~
The electronic device is characterized in that it is configured to determine the sample voltage (V_s) from the secondary electron signal (S) obtained by φ_n) with reference to the S curve (C_0) stored in the memory. Beam device.