JPS6376251A - Sample stage for scanning electron microscope - Google Patents

Abstract

PURPOSE:To obtain a sample stage in which the movement of the observation point following to the rotation can be corrected automatically, by furnishing a detecting means to detect the rotation center position of a rotary shaft, an arithmetic means to compute the movement distance of the observation point on the sample surface, and a correcting means to correct the movement of the observation point automatically. CONSTITUTION:The rotation center of a sample is regulated mechanically beforehand to be at the beam irradiating position, and by resetting the value of a detecting circuit 18 at zero at the starting of the operation, the beam irradiating position is registered as the origin. A sample movement operation circuit 19 is a circuit by which the operator degignates the parallel movement and the rotation of the sample through a consol or the like. The designated operating amount is output to a system control circuit 17, and the operation is carried out responding to the operating amount. An observation point movement arithmetic circuit 20 is to read the coordinates of the rotation center before the rotating operation from the detecting circuit 18 when the rotation amount is input from the operation circuit 19, to compute the movement amount of the observation point, and to output the result to the system control circuit 17. Therefore, the operation to return the observation point to the beam irradiating position can be carried out automatically.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a rotatable sample stage for a scanning electron microscope (hereinafter referred to as sample stage).

(Prior Art) Some sample stages are capable of rotating the sample in addition to movement in the x-y-z directions. One of these axes is adjusting the relative positional relationship between the sample surface and the secondary electron signal detector by rotation.

FIG. 3 shows a schematic configuration of a conventional sample stage.

That is, a holder 2 holding a sample 1 is supported by a rotating shaft 3, and a holder branch portion 5 on which the rotating shaft 3 and its rotational drive mechanism 4 are mounted moves in parallel on an XY table 6. 7, the scanning electron beam irradiation position is fixed. A minute portion of the sample 1 that is irradiated with the scanning electron beam 7 is displayed as an image WRa.

(Problems to be Solved by the Invention) In the conventional sample stage, the position on the surface of the sample 1 that is irradiated with the scanning electron beam 7 is an arbitrary position on the sample 1, and therefore does not normally coincide with the center position of the rotation axis 3. The problem that occurs when the sample stage is rotated in order to rotate the direction of the currently observed image by an angle θ in this mismatched state will be explained based on FIG. 4.

8 is the rotation center of the sample 1, 9 is the irradiation position of the scanning electron beam 7, and 10 is the position to which the am point, which was at the irradiation position before rotation, moves when the sample 1 is rotated by an angle θ. In this way, the observation point 10 shifts from the beam irradiation position 1i9 as it rotates, so conventionally, after one rotation, the operator does not search visually and moves the sample stage in parallel by trial and error until an image at point 10 is obtained. As a result, there was a problem in that it was necessary to return the Wt base point 10 to the beam irradiation position 9.

The purpose of the present invention is to solve this problem.

It is an object of the present invention to provide a sample stage that automatically corrects the movement of the am point due to rotation.

[Structure of the invention]

(Means for Solving the Problems) FIG. 1 is a block diagram of the sample stage of the present invention. 11 is a means for detecting the position of the center of rotation of the sample using a sensor; 12 is a means for obtaining rotation operation instructions and detecting the rotation center position of the sample;
l! Means for calculating the observation point base point movement, 13 is IIIM that moves with rotation! ! The sample stage according to the present invention is comprised of means for performing correction control to return the point to the beam irradiation position.

(Function) The function of each means constituting the present invention in FIG.
i! This will be explained with reference to i. Here, in FIG. 4, for the sake of convenience, an X-Y coordinate system with the beam irradiation position 9 as the origin will be considered. The position of the rotation center 8 in sample 1 is
Changes due to Y parallel movement.

The rotation center position detection means 11 detects the amount of parallel movement of the sample 1 using a sensor, calculates and stores the coordinates (a, b) of the rotation center 8. The movement amount calculating means 12 of the observation point receives the rotation operation instruction amount θ of the sample 1, and calculates I! along with the rotation along with the above coordinate information. Movement amount ΔX in the X direction and Y direction of the observation point 10.

Calculate Δy using each of the four formulas ① and ② and store it.

1Δxl=lpsin(θ÷90°−α)−al ・・
・■1Δyl = I #cos (θ÷90°−a)
−b l −■Here α=Tan−” (−)
...■The correction control means 13 for the am point uses the above-mentioned movement amount information ΔX.

Using Δy, beam irradiation position to the moving w4 observation point 10! i! Sample 1 is moved in parallel to return to 9.

(Example) An example of the present invention will be described below with reference to the drawings.

In FIG. 2, reference numeral 16 denotes a sample stage mechanism section, the details of which are shown in FIG. 3. Reference numeral 17 denotes a control circuit for the mechanical section, which controls the sample to move in parallel and rotate by driving a motor. Reference numeral 18 denotes a rotation center position detection circuit that detects the amount of change in movement of the first mechanical part 16 using a sensor such as an encoder, and calculates the coordinates of the rotation center of the sample when the beam irradiation position is set to the X-Y point mW. ,Remember. Here, the method of setting the beam irradiation position as the origin is as follows. That is, in the state at the start of operation of the mechanism section 16, the rotation center of the sample is adjusted mechanically in advance so as to be at the beam irradiation position, and the value of the detection circuit 18 is reset to zero at the start of operation. By doing this, the beam irradiation position can be registered as the origin.

Reference numeral 19 denotes a sample movement operation circuit, which is used by an operator to specify parallel movement and rotation of the sample using a console or the like. The specified operation amount is output to the mechanism control circuit 17, and the corresponding operation is executed.

20 is 11! When the detection point movement amount calculation circuit receives the input of the amount of rotational movement from the operation circuit 19, the coordinates of the center of rotation before the rotational movement are read from the detection circuit 18.

Based on (2), the amount of movement of the base point a is calculated and outputted to the mechanism control circuit 17. As a result, the operation of returning the base point a to the beam irradiation position is automatically performed.

[Effects of the Invention] As explained above, according to the present invention, the movement of the observation point during sample rotation is automatically corrected, so that efficient m
This has the effect of enabling s.

[Brief explanation of the drawing]

FIG. 1 is a block configuration diagram of the present invention, FIG. 2 is a schematic explanatory diagram of an embodiment of the present invention, FIG. 3 is a configuration diagram of a conventional sample stage, and FIG. 4 shows the problems and problems of the conventional sample stage. FIG. 2 is a diagram illustrating the present invention in detail. 1... Sample 2... Holder 3...
・Rotation axis 8...Rotation center 9...Beam irradiation position [10...Observation point 16...Sample stage mechanism 17...4! & Structure control circuit 18...Rotation center position detection circuit 19...Sample movement operation circuit 20
... Observation point movement amount calculation circuit agent Patent attorney Nori Chika Ken Yudo Hirofumi Mitsumata Figure 1 Figure 2

Claims (1)

[Claims] In a rotatable sample stage for a scanning electron microscope, a detection means detects a rotation center position of the rotation axis, and a calculation means calculates a movement distance of an observation point on a sample surface from the rotation center position and a rotation angle of the rotation axis. , and correction means for automatically correcting the movement of the observation point based on the calculation result of the calculation means.