JPH0574902B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an improvement in an analysis device using a charged particle beam.

[Prior Art] For example, in an Auger electron spectrometer using an ion beam, the sample is analyzed by irradiating the vicinity of the ion beam irradiation point with the electron beam while scanning the sample surface with the ion beam and etching the sample surface.

In such a device, when the sample is an insulator, etc., in order to prevent charge up due to electron beam irradiation and obtain a highly accurate Auger spectrum,
Furthermore, when analyzing information on the very surface of a metal sample, the sample is tilted for analysis.

However, in such a device, the scanning direction of the ion beam is always set in a fixed direction with respect to the ion gun, so if the sample is tilted in any direction from the horizontal direction, the scanning direction of the ion beam on the sample may change. The direction will change depending on the tilt angle of the sample.

[Problems to be Solved by the Invention] In the conventional apparatus configured as described above, the sample S is placed perpendicular to the electron beam irradiation axis (optical axis) Z, as shown in FIG. , when the ion irradiation area A of the ion beam that etches the surface of the sample S is square-shaped when viewed from the optical axis Z direction, the electron beam irradiation area B irradiated from the optical axis Z direction is within the ion irradiation area A. is irradiated.

However, when the sample S is tilted, the shape of the ion irradiation area A gradually changes to a parallelogram shape that is a squashed rectangle, and when the tilt angle θ with the X axis of the sample as the tilt axis is further increased, the optical axis The shape of the ion irradiation area A when viewed from the Z direction becomes narrow in a substantially straight line as shown in FIG.

Therefore, for example, when performing sample analysis by irradiating the ion beam irradiation area A with an electron beam, if the inclination angle θ of the sample becomes large, the ion beam irradiation area A
becomes narrower, and the area other than the ion irradiation area A, that is, the ion irradiation area A where no etching is performed.
Analyzing other areas as well.

Therefore, in conventional equipment, when analyzing a sample while tilting the sample, the scanning width of the ion beam is widened to cover the electron beam irradiation area B.
As shown in the ion beam irradiation area A' in the figure, an unnecessarily large area must be etched. Therefore, etching takes time and, as a result, analysis requires a long time. Also, the sample inclination angle θ
Since the shape of the ion irradiation area A changes accordingly, the ion beam scanning width must be adjusted each time, resulting in a disadvantage that the analysis operation becomes complicated.

The present invention was made in view of the above points, and even if the sample is tilted arbitrarily, the ion beam scanning direction is changed according to the sample tilt angle θ, and even if the sample tilt angle θ is changed, the ion beam scanning direction is changed. It is an object of the present invention to provide an apparatus in which the etching time using an ion beam is shortened by keeping the horizontal and vertical scanning directions unchanged, thereby shortening the analysis time and simplifying the analysis operation.

[Means for Solving the Problems] In order to achieve this object, the present invention provides a means for irradiating a sample with a charged particle beam for analysis, and a means for analyzing an information signal obtained from the sample based on the irradiation. an irradiation means for irradiating an etching ion beam onto the surface of the sample to which the charged particle beam is irradiated; a deflector for deflecting the ion beam from the irradiation means; An apparatus comprising: means for supplying scanning signals for horizontal and vertical scanning to the deflector; and sample tilting means for tilting the sample; axis, Y axis, and Z axis are fixed coordinate axes with respect to the analyzer, and when the charged particle beam irradiation means for analysis is fixed on the Z axis, the inclination angle of the ion beam irradiation means with respect to the YZ plane and signals representing the inclination angle with respect to the XY plane, respectively, are supplied to the deflector so that the horizontal and vertical scanning directions of the ion beam on the sample surface always remain unchanged regardless of the inclination of the sample. It is characterized by comprising means for controlling the deflection signal.

[Example] Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention. 1
is an ion gun; 2 is an ion beam emitted from the ion gun 1; the ion beam 2 is deflected by a deflection electrode 3 and scans over a sample 4; As shown in FIG. 2, the deflection electrodes 3 include deflectors 3a, 3b and 3c, 3d for scanning in mutually orthogonal directions.
It is composed of Reference numeral 5 denotes an electron gun disposed on the optical axis Z, and an electron beam 6 that irradiates the sample 4 is emitted from the electron gun 5. 7 is a scanning signal generation source that generates sawtooth wave X-axis scanning signals and Y-axis scanning signals; 8 and 9 are gain adjustment circuits for varying the scanning amplitude of the scanning signals from the scanning signal generation source 7; . 10 and 11 are multipliers into which the scanning signal from the gain adjustment circuit is input; 12 and 13 are adders;
14 and 15 are scanning signal inversion circuits; 16 is a sample stage for tilting the sample 4; and 17 is a drive circuit for supplying a drive signal to the sample stage 16. 18 is an arithmetic control device that performs various arithmetic controls;
19 is a keyboard for inputting various parameters to the arithmetic and control unit 18; Reference numerals 20 and 21 are D/A converters for converting the digital signal of the calculation result from the calculation control unit 18 into an analog signal and supplying the analog signal to the multiplier.

In the apparatus configured as described above, the positional relationship of the ion gun 1, sample 4, and electron gun 5 is shown in FIG. In FIG. 3, the X-axis, Y-axis, and Z-axis are fixed coordinates with respect to the analyzer, the electron gun 5 is provided on the Z-axis (optical axis), and the sample stage 16 is located on the optical axis Z. A sample 4 placed on the surface is placed. Although not shown in FIG. 1, on the electron beam optical axis immediately above the sample 4, that is, on the Z axis, there is an objective lens for focusing the electron beam for analysis onto the sample surface. Means (for example, an energy analysis system) for analyzing information signals obtained from the sample are provided on the Y-axis immediately above the sample 4, and even if the sample is tilted, it will not remain on the sample. The ion source 1 is irradiated with an ion beam.
It is arranged at a position inclined by an angle a with respect to the YZ plane and an angle b with respect to the XY plane. x axis, y axis,
The z-axis is a coordinate fixed to the ion gun 1, and the x-axis of the fixed coordinate of the ion gun 1 passes through the origin O of the X, Y, Z coordinate system. Therefore, the arrangement relationship between the deflection electrode 3 and each x-axis, y-axis, and z-axis shown in FIG. 2 is such that the irradiation axis (optical axis) of the ion beam coincides with the Deflector 3
Deflectors a and 3b are arranged perpendicular to the z-axis, and deflectors 3c and 3d are arranged perpendicular to the y-axis. Also, the y-axis of the fixed coordinates of the ion gun 1 is Y
Although not parallel to the axis, it is parallel to the XY plane and perpendicular to the x axis, and the z axis is perpendicular to the x and y axes. The X′ axis, Y′ axis, and Z′ axis are coordinates fixed to the sample.
It is determined to coincide with the X, Y, and Z axes when the inclination angle θ=0. Also, the inclination angle θ is the fixed coordinate system XY
The angle formed by the plane and the sample surface, φ, is the angle fixed to the sample.
This is the angle between the Y′ axis and the horizontal scanning direction of the ion beam.

Now, as shown in Fig. 4, when the angle formed by one scanning direction of the ion beam and the y-axis is ω ₁ , when θ changes in the range of 0°≦θ≦90°, the When considering what conditions must be imposed on ω ₁ in order to always maintain the state of φ=0 as shown in FIG. 5, the following conditions are obtained.

ω ₁ = tan ^-1 {sin b/tan a+(cos b/sin a)・
tanθ}……(1) Also, if ω ₂ is the angle formed by the other scanning direction of the ion beam and the y-axis, when θ changes in the range of 0°≦θ≦90°, the sample The conditions required for ω ₂ to maintain the ion beam vertical scanning direction on the surface at 90° with respect to the Y′ axis are as follows.

ω ₂ = tan ^-1 (−sin b/tan a) ...(2) In the above equation, the right side is a constant, so ω ₂ only needs to be set to the value given by the above equation from the beginning, It is sufficient to change only ω ₁ according to θ.

In FIG. 4, if the amount of deflection of the ion beam in the y direction is V ₁ and the amount of deflection in the z direction is V ₂ , then the ratio R of the amount of deflection in both directions to achieve the above-mentioned ω ₁ is
is R=V ₂ /V ₁ = tanω ₁ = sin b/tan a) + (cos b/
sin a)・tanθ...(3)

Based on this relationship, in the apparatus of the embodiment shown in FIG. tilt only. Further, the arithmetic and control unit 18 calculates R in equation (3) based on equation (3) based on the inclination angle θ, outputs the result to the D/A converter 20, and outputs the result to the D/A converter 20.
A constant ratio value signal corresponding to the above equation (2) is sent to the converter 21. The signals converted into analog signals by the D/A converter are supplied to multipliers 10 and 11. The multipliers 10 and 11 multiply the output signals of the D/A converters 20 and 21 by the X-axis scanning signal and the Y-axis scanning signal, respectively. Therefore, the multiplier 10 adjusts the amplitude of the X-axis scanning signal according to the tilt angle θ. The X-axis scanning signal and the Y-axis scanning signal from these multipliers 10 and 11 are added to the Y-axis scanning signal and the X-axis scanning signal in adders 12 and 13, respectively, and the scanning signal from the adders 12 and 13 is teeth,
The signals are supplied to the deflector 3 via inverting circuits 14 and 15, respectively.

Therefore, even if the sample 4 is tilted arbitrarily, the angle φ between one scanning direction of the ion beam on the sample surface and the Y' axis will be φ=0, and the other one will be φ=0 depending on the sample tilt angle θ. The ion beam is scanned so that the angle between the scanning direction and the Y' axis satisfies the condition of 90 degrees. Therefore, as shown in FIG. 5, the ion irradiation area A includes the electron beam irradiation area B of the electron beam 6, and areas other than the ion irradiation area are not analyzed. Also, in some cases, even if the width of the ion beam irradiation area becomes narrow and the electron beam irradiation area B protrudes from the ion irradiation area A, the direction in which the irradiation area B extends will always match the scanning direction of the ion beam on the sample. Since it is parallel to the direction, it is only necessary to adjust the gain adjustment circuits 8 and 9 to slightly widen the ion irradiation area.

Therefore, unlike the conventional apparatus, there is no need to widen the scanning width of the ion beam to unnecessarily enlarge the ion beam irradiation area, and therefore no time is required for etching.

The above embodiments are illustrative and can be implemented in other ways. In the above embodiment, the tilt angle θ is input using the keyboard, but the tilt angle of the sample stage may be detected and automatically controlled based on the signal.

[Effects of the Invention] As detailed above, the present invention provides a signal representing the tilt angle of the sample, and the X-axis, Y-axis, and Z-axis are fixed coordinates with respect to the analyzer, and the charged particle beam for analysis is When the irradiation means is fixed on the Z-axis, the inclination angle of the ion beam irradiation means with respect to the YZ plane is
Based on each signal representing the inclination angle with respect to the XY plane, the signals are supplied to an ion beam deflector so that the horizontal and vertical scanning directions of the ion beam on the sample surface always remain unchanged regardless of the inclination of the sample. Since a means for controlling the deflection signal is provided, the ion beam irradiation means for etching is placed at a predetermined position above the sample, which is different from the charged particle beam irradiation means for analysis and the means for analyzing information signals obtained from the sample. Even if the sample is tilted arbitrarily in the case where Since the electron beam irradiation area can be maintained within the etching area by simply widening the area, the etching time using the ion beam is shortened, and therefore the analysis time is shortened.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of the present invention, FIG. 2 is a diagram for explaining the deflector, FIGS. 3 and 4 are diagrams for explaining the present invention, and FIG. 5 is a diagram for implementing the present invention. FIGS. 6 and 7 are diagrams for explaining the ion irradiation area and the electron beam irradiation area, and FIGS. 6 and 7 are diagrams for explaining the conventional apparatus. 1: Ion gun, 2: Ion beam, 3: Deflector, 4: Sample, 5: Electron gun, 6: Electron beam,
7: Scanning signal generation source, 8, 9: Gain adjustment circuit,
10, 11: Multiplier, 12, 13: Adder, 1
4, 15: Scanning signal inversion circuit, 16: Sample stage, 17: Drive circuit, 18: Arithmetic control unit, 1
9: Keyboard, 20, 21: D/A converter.

Claims (1)

[Claims] 1 means for irradiating a sample with a charged particle beam for analysis, means for analyzing information signals obtained from the sample based on the irradiation, and means for applying an ion beam for etching to the surface of the sample to which the charged particle beam is irradiated. irradiation means for irradiating the ion beam, a deflector for deflecting the ion beam from the irradiation means, and means for supplying a scanning signal to the deflector for scanning the ion beam horizontally and vertically on the sample surface. and a sample tilting means for tilting the sample, wherein a signal representing the tilt angle of the sample, and X-axis, Y-axis, Z-axis
When the axis is a coordinate axis fixed to the analyzer and the charged particle beam irradiation means for analysis is fixed on the Z axis, the YZ of the ion beam irradiation means
The deflector is configured so that the horizontal and vertical scanning directions of the ion beam on the sample surface always remain unchanged regardless of the inclination of the sample, based on signals representing the inclination angle with respect to the plane and the inclination angle with respect to the XY plane, respectively. 1. An analysis device using a charged particle beam, characterized by comprising means for controlling a deflection signal supplied to the charged particle beam.