JPH02276144A - Electron beam device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] To accurately deflect the electron beam to an actual position by quickly and easily setting the deflection amount of the electron beam during beam irradiation (for example, during measurement) regarding an electron beam device. The purpose of the present invention is to provide an electron beam device that deflects an electron beam by a deflection means including a deflection coil and irradiates an arbitrary position on a sample. coordinate data setting means for setting a position number corresponding to as coordinate data, a deflection coordinate when an electron beam is irradiated to a position on a sample specified by the coordinate data, and a deflection coordinate corresponding to a regular irradiation position; a correction data setting means for setting correction data for correcting the amount of deflection of the electron beam according to the displacement of the coordinate data; and a deflection control current generation means for correcting the electron beam by inputting a position number on the sample, the deflection means deflects the electron beam to a corresponding position based on the output of the deflection control current generation means. Configure.

[Industrial application field]

The present invention relates to an electron beam device, and more particularly, to an electron beam device that is applied to an electron beam tester and the like, and has an improved setting of the amount of electron beam deflection.

With the increasing density of LSIs, the number of internal elements per external terminal has reached 5,000 (=1 million elements/200 terminals). For this reason, it has become difficult to identify the location of a failure or understand its cause using only input/output tests using ordinary LSI test equipment, and a means to directly measure the internal operating state of the LSI has become necessary. However, now that the wiring width has become less than a few microns, the stylus force used to measure the voltage by bringing a metal probe into contact with the internal wiring is no longer applicable.

Against this background, electron beam (t!11: el
Electron beam applied testing techniques using an electr-on beam (electr-on beam) as a probe have come into use. This is a scanning electron microscope (SBM).
This is a technology that performs tests by directly measuring the wiring potential inside an LSI by using the potential contrast observed with a G-electron ML-Croscope.

This technology has the advantage of being non-contact, non-destructive, and allows for raw measurements without introducing a capacitive load into the measurement system.

When measuring LSI signals using such an electron beam device, when there are many points to be measured, it takes a lot of time and effort to teach the deflection amount one by one, so quick deflection amount setting is required. has been done.

[Conventional technology]

When measuring LSI signals with a conventional electron beam device, for example, as shown in Fig. 4, many wires l connected to the LSI (paths shown in the diagram) are received by terminals (pads) 2, and these are used as measurement terminals in a square. A large number of electron beams are arranged in a shape, and the electron beam is sequentially applied to these terminals 2 while changing the amount of deflection.
We are measuring the behavior of I. The measurement terminals shown in FIG. 4 have a three-dimensional structure in which each wiring 1 passes through from below each terminal 2 and is connected to an inner terminal. In this case, the amount of deflection of the electron beam toward the measurement point, that is, the terminal 2, is set by the operator each time the measurement is made, or is registered in advance before the measurement.

[Problem to be solved by the invention]

However, with such conventional electron beam devices, the amount of deflection toward the measurement point must be set by the operator each time a measurement is made, or it must be registered in advance before measurement, which is time-consuming and troublesome. Therefore, there was a problem in that the amount of deflection could not be set quickly during measurement.

In particular, when there are many points to measure, such as when measuring LSI signals, depending on the stability of the optical system, it may be necessary to teach the amount of deflection one by one immediately before measurement. This is time consuming and unrealistic.

On the other hand, in electron beam exposure equipment used on LSI manufacturing lines, there is a method of matching data coordinates and deflection coordinates by teaching representative points, but distortion of the deflection surface due to lens aberrations, deflection aberrations, etc. must also be taken into account. In some cases, higher-order equations must be solved, and many points need to be taught. Therefore, even if this method is used, it is still time-consuming and cannot be said to be quick. There is also a method of dividing the problem into several areas and taking measures, but even in this case, it is necessary to teach many points, and it is not an effective solution.

Therefore, an object of the present invention is to provide an electron beam device that can quickly and easily set the deflection amount of the electron beam during beam irradiation (for example, during measurement) and accurately deflect the electron beam to the actual position. The purpose is

[Means to solve the problem]

In order to achieve the above object, an electron beam device according to the present invention is an electron beam device that deflects an electron beam by a deflection means including a deflection coil and irradiates an arbitrary position on a sample, corresponding to the position to be irradiated on the sample. a coordinate data setting means for setting a position number to be irradiated as coordinate data, a deflection coordinate when an electron beam is irradiated to a position on a sample specified by the coordinate data, and a displacement between the deflection coordinate corresponding to the regular irradiation position; a correction data setting means for setting correction data for correcting the deflection amount of the electron beam according to the coordinate data; and a correction data setting means for generating a deflection control current for deflecting the electron beam based on the coordinate data, and correcting this according to the correction data. a deflection control current generating means, the deflection means comprising:
By inputting a position number on the sample, the electron beam is deflected to the corresponding position based on the output of the deflection control Il current generating means.

[Effect]

In the present invention, when a position number corresponding to a position to be irradiated on a sample is inputted as coordinate data, a deflection control current is generated based on the coordinate data, this is corrected according to correction data, and an electron beam is placed at the corresponding position. The beam is deflected and irradiated.

Therefore, the operator's involvement in specifying the deflection point during beam irradiation is reduced, and the electron beam can be quickly and accurately deflected simply by providing a position number.

〔Example〕

Hereinafter, the present invention will be explained based on the drawings.

1 to 3 are diagrams showing one embodiment of an electron beam device according to the present invention, and are examples in which the present invention is applied to a device for measuring LSI signals. FIG. 1 is a diagram showing the configuration of a deflection coordinate setting section in an electron beam device. In this figure, 11 is a coordinate data storage memory (coordinate data setting means), and 12 is a correction data storage memory (correction data setting means). be.

The coordinate data storage memory 11 stores the coordinates (x
. The coordinates are (X+, y
+) to (x7° yn), each corresponding to the position of each terminal, and when the terminal number i of the measurement terminal is input, the corresponding coordinate data (x=r Y+) is output.

The correction data storage memory 12 stores correction data (ΔXI+ Δy+ ) to (
Δx1. Δyb) is stored, and this is done by registering it using the program shown in FIG. 3 later. Correction data storage memo Also in January 2, if you input the terminal number i of the measurement terminal, the corresponding correction data (ΔXi,
Δy=) is output.

The coordinate data and correction data are input to a deflection current control circuit (deflection control current generation means) 13, and the deflection current control circuit 13 includes eight amplifiers 14a to 14d, 15a to 1.
5d, multiplication circuits 16.17 and addition circuits 18.19. Amplifiers 14a-14d, 15a-15
d is the actual deflection coordinate (
The output of the amplifier 14a=14d is sent to the adder circuit 18, where it is added to the correction data ΔX from the correction data storage memo 1J12 to control the deflection coil in the X direction. It is output as a current to the X-direction deflection coil 21 via the buffer 20. On the other hand, the outputs of the amplifiers 153 to 15d are sent to the adder circuit 19, added to the correction data Δy from the correction data storage memory 12, and outputted to the Y-direction deflection coil 23 via the buffer 22 as a Y-direction deflection coil control current. be done. Note that the multiplication circuits 16 and 17 are both for generating data xy. The X-direction deflection coil 21 and the Y-direction deflection coil 23 electromagnetically deflect the focused electron beam emitted from the electron gun in the X direction and the Y direction, respectively, and apply the electron beam to a predetermined measurement terminal. It consists of

In the above configuration, when trying to measure LSI signals using the measurement terminals shown in Figure 4 connected to the LSI as a measurement sample, the data coordinate system such as the design drawing of the measurement sample is used as shown in Figure 2. The actual deflection coordinate system (X, Y) corresponds to (x, y), and 25 represents the SEM image. In addition, in the figure, p (xp, yp) is P
An example of deflection to (Xp, Yp) is shown.

Conversion from the data coordinates to the deflection coordinate system is calculated by the following equation (2), and is performed by the deflection current control circuit 13.

Each coefficient Collfl~Comf4, Coafl in formula 0
l t+wcO@f14 is the 4 points of the data coordinate system (as
bs C% d) and the four points of the deflection coordinate system (A, B, C,
It is determined from the correspondence with D), but these four points (a, b, c
, d) are predetermined, and the corresponding (A, B
, C, D) are counted by the operator. Equation 0 approximates the deflection coordinate system with a trapezoid, but in reality, the trapezoid cannot fully approximate the deflection coordinate system due to lens aberrations, etc., so errors occur in the deflection coordinates as shown in FIG.

Therefore, in this embodiment, the deflection coordinates are actually measured for each measurement terminal based on the calculated coordinate values, and the displacement from the calculated values is determined and saved as correction data. Then, during measurement, accurate deflection is performed by taking into account the coordinate calculation values of the specified terminal.

Specifically, when the terminal number i corresponding to the terminal to which the electron beam is to be irradiated is entered into the coordinate data storage memory 11 and the correction data storage memory 12, the coordinate data (Xe) is entered from the coordinate data storage memo January 1.

yl is read out, and the deflection current control circuit 13 sets the value to 0.
After the deflection coordinates <X, Y) are calculated according to the formula, the correction data (ΔXi+Δ
y=> is read and the deflection coordinate (X.

Y) is corrected and a deflection coil control current is output to the X-direction deflection coil 21 and the Y-direction deflection coil 23. As a result, the electron beam is deflected, and the electron beam is irradiated toward the measurement terminal corresponding to the terminal number i, thereby measuring the signal of the LSI.

Here, coordinate data, correction data, deflection current control circuit 1
Amplifiers 14a-14d, 15a in 3
The gain of 15d is set in advance, and the coordinate data is obtained from a design drawing as described above, but the amplifier gain and correction data are registered according to the procedure shown in FIG.

That is, in FIG. 3, all contents of the correction data storage memory 12 are reset to "0" as an initial state. First, Pl (points to the step of the program).

The same applies hereafter)) on the data coordinates (a, b, c-, di
The deflection coordinates (A, B, C5D) corresponding to the SEM image 25
Specify above. This corresponds to a process of predetermining (as bs C5d) as a representative point and specifying its deflection position. Next, at P2, the deflection is determined from the data coordinates of the representative point and the corresponding deflection coordinates, and the amplifier 1 of the current control circuit 1319 is calculated.
Calculate and set the gains of 4a-14d and 15a-15d. After setting the gain in the deflection current control circuit 13, P
, enter 1 into the terminal number i, and read the coordinate data (X=+yi) of the terminal i from the coordinate data storage memo January 1 at P4 and send it to the deflection current control circuit 13. As a result, deflection coil control currents in the X and Y directions are generated in the deflection current control circuit 13 and sent to the X direction deflection coil 21 and the Y direction deflection coil 23, and the electron beam is deflected and irradiated onto the deflection position. Next, coordinate data (x! +
Line scanning is performed centering on the deflection position corresponding to '/=), the center of gravity of the current terminal i is determined from the scan data at P, and the deflection corresponding to this center of gravity and the correct coordinates (regular irradiation position) of terminal i is calculated. The difference (displacement) (Δxi+Δy1) from the coordinates (Xi, Yi) is calculated, and this is stored as correction data in the correction data storage memo January 2. That is,
By performing line scans in each of the x and y directions centering on the deflection coordinates obtained by inputting the terminal number i into the coordinate data storage memory 1■, changing the correction data so that the center of gravity is at the center. Find the displacement, which is (ΔX
i, Δyl.

Next, increment the terminal number i at P, and increment the terminal number i at P8.
Determine whether or not the number has reached a predetermined number n (total number of terminals), and
If o, return to P3 and repeat the above process. On the other hand, i
>n, the registration process ends.

In this way, in this embodiment, once several points are registered as representative points, all that is left is to give the terminal number i, and at the time of measurement, the correction data (Δx8, Δyl are appropriately added to the coordinate calculation values of the specified terminal, and the amount of deflection is calculated. This allows the electron beam to be accurately deflected to the actual terminal.Therefore, the operator's involvement in specifying the deflection point is extremely reduced.
By performing deflection quickly and simply during measurement, LSI signal measurements can be quickly performed.

Note that the application of the present invention is not limited to the LSI signal i1+1 constant as in the above embodiment, but may be applied to other fields. It is possible.

Further, the number of representative points is not limited to four as in the above embodiment, but may be any other suitable number.

〔Effect of the invention〕

According to the present invention, there is little operator involvement during electron beam irradiation, and the amount of deflection of the electron beam can be quickly and easily set simply by providing a position number, thereby accurately deflecting the electron beam to the actual position. be able to.

[Brief explanation of drawings]

1 to 3 are diagrams showing an embodiment of the electron beam device according to the present invention, FIG. 1 is a diagram showing the configuration of the deflection coordinate setting part, and FIG. 2 is a diagram showing the correspondence of the coordinates. , FIG. 3 is a flowchart showing the data registration procedure, and FIG. 4 is a diagram showing an example of a measurement terminal that irradiates an electron beam. 25...SEM image. 11... Coordinate data storage memory (coordinate data setting means), 12... Correction data storage memory (correction data setting means), 13... Deflection current control circuit (deflection control current generation means), 14a to 14d, 15a to 15d-... amplifier, 16.17... multiplier circuit, 18.19... adder circuit, 20.22...・Buffer, 21...X direction deflection coil, 23...Y direction deflection coil, 24...Deflection means, (a) Data coordinate system (b) Scan coordinate system - Diagram 21 showing the correspondence of coordinates in the example Flowchart showing the data registration procedure in the example

Claims (2)

[Claims] (1) In an electron beam device that deflects an electron beam by a deflection means including a deflection coil and irradiates an arbitrary position on a sample, a coordinate system in which a position number corresponding to a position to be irradiated on the sample is set as coordinate data. data setting means, and correcting the amount of deflection of the electron beam according to the displacement between the deflection coordinate when the electron beam is irradiated to the position on the sample specified by the coordinate data and the deflection coordinate corresponding to the regular irradiation position. and a deflection control current generating means for generating a deflection control current for deflecting the electron beam based on the coordinate data and for correcting the deflection control current according to the correction data. . An electron beam apparatus, wherein the deflection means receives a position number on the sample and deflects the electron beam to a corresponding position based on the output of the deflection control current generation means. (2) The deflection control current generating means specifies the deflection positions of the representative points determined as the position numbers, thereby making correspondence between the coordinates corresponding to the position numbers and the electron beam deflection coordinates, and controlling the deflection from this point. 2. The electron beam device according to claim 1, wherein the electron beam device generates an electric current.