JPH0232741B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel sample image display device used in a charged particle beam device.

An irradiation beam such as an electron beam or ion is used to scan the sample surface, and the signal detected from the sample is synchronized with the scanning and is used as a brightness modulation signal to display the sample image on the CRT screen. This has been practiced for a long time, and a typical example is a scanning electron microscope. In this scanning electron microscope, it is often required not only to frequently move the field of view of the sample image displayed on the CRT screen, but also to rotate the field of view. To move the field of view of the sample image on the CRT screen, a sample movement mechanism is used that moves the sample in two mutually orthogonal directions in a plane perpendicular to the irradiated electron beam, but as a means to rotate the field of view, Since it is difficult to mechanically rotate the sample with high precision, a device that rotates the direction of scanning of the electron beam irradiating the sample by electrical means is widely used as a simple means for rotating the field of view. However, when such a field of view rotation means is used, the relationship between the direction of movement of the sample by the sample moving mechanism and the direction of movement of the field of view on the CRT screen changes, which has the disadvantage of making it difficult to operate the field of view selection.

The purpose of the present invention is to solve these drawbacks and maintain a constant relationship between the sample movement operation and the field of view movement direction within the CRT screen even if the sample scanning direction by the irradiation beam is rotated. includes a deflection means consisting of two deflection elements for deflecting the irradiation beam in two mutually orthogonal directions on the sample surface; a scanning signal circuit that supplies a scanning deflection signal to the deflection means via a rotation circuit; rotation signal generating means for supplying a rotation signal to a circuit; scanning image display means to which an output of the scanning signal circuit is supplied; and for moving the sample in two mutually orthogonal directions within a plane perpendicular to the irradiation beam. a sample moving mechanism consisting of two electrical moving means; a sample moving signal generating means for specifying the moving direction and moving speed of the sample by the sample moving mechanism; an output signal of the sample moving signal generating means; and the rotation signal. The present invention is characterized in that it includes a central control circuit that provides drive signals to the two electric moving means based on the rotation signal supplied from the generating means.

FIG. 1 is a schematic diagram showing an apparatus according to an embodiment of the present invention.
In the figure, numeral 1 represents a sample, which is irradiated with an electron beam from the optical axis Z direction. A scanning signal from a scanning signal circuit 3 is supplied to the deflection coils 2x and 2y for the electron beam via a rotation circuit 4, and when no rotation signal is supplied to the rotation circuit 4, the deflection coils 2x and 2y are deflected in the x and y directions of the sample surface. Scanned in two dimensions. Two pulse motors 6H and 6V are attached to the sample moving mechanism 5 on which the sample 1 is placed, as electric moving means, and the sample 1 is moved in two directions perpendicular to each other by driving the pulse motors 6H and 6V. It moves to H and V, but the directions of H and V are adjusted to match the x and y directions. In addition, the deflection coil 7X of the CRT 7 used as a scanning image display means,
A scanning signal from the scanning signal circuit 3 is supplied to 7Y, and a detection signal from the specimen is given as a brightness modulation signal for the CRT screen, so that a scanned image of the specimen is displayed on the CRT screen. A signal from a rotation signal generation means 8 is supplied to the rotation circuit 4, and by operating the rotation signal generation means 8, the sample scanning direction on the sample is rotated and the field of view within the CRT screen is arbitrarily rotated. be able to. on the other hand
In order to move the field of view of the CRT screen, the movement signal generation means 9 that generates sample movement signals in the X and Y directions is operated, and the output signal from the movement signal generation means 9 is sent via the central control circuit 10. and supplies it to the pulse motor drive circuits 11H and 11V. A rotation signal from the rotation signal generation means 8 is also supplied to the central control circuit 10, and the drive circuit 11 is controlled based on the input signal from the movement signal generation means 9 and the rotation signal.
Determine the control signal to be supplied to H, 11V. Second
The figure shows the scanning directions x, Y of the irradiation beam on the sample surface, based on the CRT screen scanning directions
y and the sample movement directions H and V by the pulse motors 6H and 6V.As mentioned above, the directions H and V coincide with the directions x and y, respectively, so both the directions Match. This means that when the pulse motor 6H is driven, the field of view within the CRT screen moves in the horizontal (X) direction, and the pulse motor 6V
This means that the field of view within the CRT screen moves in the vertical (Y) direction.

Figure 3 shows the rotation signal generation circuit 8 from the state shown in Figure 2.
It represents the change when the sample scanning direction by the irradiation beam is rotated by an angle θ by operating the to do. Therefore, the field of view on the CRT screen where the sample is moved only by the pulse motor 6H does not move in the lateral direction of the screen, but in the direction forming an angle -θ with the lateral direction X. In the device shown in FIG. 1, the output signal from the movement signal generating means 9 is not directly supplied to the drive circuits 11H and 11V of the pulse motor, but the central control circuit 10 uses the rotation signal from the rotation signal generating means 8. The processed movement signals are supplied to drive circuits 11H and 11V.
For example, if a signal represented by vector A in FIG. 4 is generated by rotating the knob in the 'X' direction of the movement signal generating means 9 in any direction at any angle, H, which forms an angle -θ with vector A, Component Ah in the V direction,
Each drive circuit 1 is converted into a signal corresponding to Av.
Supplied to 1H and 11V. As a result, the sample 1 moves in the X direction and the field of view on the CRT screen moves in the lateral (X) direction. Similarly, the movement signal generating means 9'
When the Y' direction knob is rotated by an arbitrary angle and a signal represented by vector B in Fig. 5 is generated, components in the H and V directions forming an angle -θ with the vector B
Signals corresponding to Bh and Bv are generated by the central control circuit 10 and supplied to the drive circuits 11H and 11V.
As a result, the sample 1 moves in the y direction and the field of view on the CRT screen moves in the vertical (Y) direction. That is, in the embodiment device of FIG.
The direction of movement of the field of view within the CRT screen by operating the X' direction and 'Y' direction knobs is always kept constant regardless of the field rotation operation, making it easier than before to search for the desired field of view within the sample plane. Become.

It should be noted that the present invention is not limited to the embodiment shown in FIG.
Two types of sample movement signals may be generated depending on how the joy take falls. Further, for example, +X, -X switches may be used instead of the 'X' direction knob, and +Y, -Y switches may be used instead of the 'Y' direction knob.

As explained in detail above, according to the present invention, even if the direction of sample scanning by the irradiation beam is rotated, the moving direction of the field of view in the sample image display means can always be kept constant, so that the field of view selection operation in the sample image display device can be performed This makes it possible to significantly improve performance.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an apparatus according to an embodiment of the present invention, and FIGS. 2 to 5 are schematic diagrams for explaining the operation of the apparatus shown in FIG. 1: Sample, 2x, 2y: Deflection coil, 3: Scanning signal circuit, 4: Rotation circuit, 5: Sample moving mechanism, 6
H, 6V: Pulse motor, 7: CRT, 7X, 7
Y: Deflection coil, 8: Rotation signal generating means, 9: Movement signal generating means, 10: Central control circuit, 11H,
11V: Drive circuit.

Claims (1)

[Claims] 1. A deflection means consisting of two deflection elements for deflecting the irradiation beam in two mutually orthogonal directions on the sample surface, a scanning signal circuit that supplies a scanning deflection signal to the deflection means via a rotation circuit, and rotation signal generating means for supplying a rotation signal to a circuit; scanning image display means to which an output of the scanning signal circuit is supplied; and for moving the sample in two mutually orthogonal directions within a plane perpendicular to the irradiation beam. a sample moving mechanism consisting of two electrical moving means; a sample moving signal generating means for specifying the moving direction and moving speed of the sample by the sample moving mechanism; and an output signal of the sample moving signal generating means and the rotation signal generating means. A sample image display device comprising a central processing circuit that provides drive signals to the two electrical moving means based on rotational signals supplied from the means.