JPS62209302A - Apparatus for detecting parallel moving quantity - Google Patents

Abstract

PURPOSE:To measure parallel moving quantity, by a method wherein the electrode needle fixed to the moving surface of a device parallel to the lattice plane of a monocrystal is allowed to approach the lattice plane to count the change in the potential of the electrode needle. CONSTITUTION:The arrangement of the atoms 3 on the surface F of a monocrystal 2 is fixed in parallel to the x- and y-axes of a parallel moving device. When an electrode needle 1 is allowed to approach the surface F so as to leave a gap of several Angstrom , the movement of charge due to tunnel effect is generated and the potential of the electrode needle 1 changes. Because one cycle of the change in potential coincides with the moving distance of the needle 1 corresponding to one lattice plane interval of the monocrystal 2, the change in potential is measured by a potential measuring device 4 and converted to a pulse to be counted to measure the parallel moving quantity of the electrode needle 1 at the accuracy corresponding to the lattice interval of the monocrystal.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Application The present invention relates to an ultra-precision parallel displacement amount detection device.The present invention relates to an ultra-precision parallel displacement amount detection device.In recent years, ultra-large scale integrated circuits, etc., have become increasingly dense.
With this development, there has been a demand for ultra-precise movement accuracy of parallel movement devices for workpieces, etc. Conventionally, methods for detecting the amount of parallel movement with ultra-precise human-level accuracy have been one-dimensional. The only detection method is a method using an X-ray interferometer, and there are almost no practical examples.In particular, as a means for detecting the amount of two-dimensional translation in a two-dimensional translation device, there has been no example in the past.

Problems to be Solved by the Invention The purpose of the present invention is to enable detection of the two-dimensional movement amount of a parallel movement device when performing parallel movement with ultra-precise accuracy on the order of λ. do. 2. Means for solving the problem: one lattice plane of a very high-quality single crystal whose lattice spacing is known is exposed on the surface, and it is fixed or linked to a moving device having a moving plane parallel to the same surface. When the tip of an extremely thin electrode needle is brought close to the surface on the order of a human being and the needle is moved along the surface, the change in potential caused by the charge flowing into or out of the electrode needle is measured. A potential measuring device was installed to detect and count.

According to the present invention, when an electrode needle with an ultra-sharp tip is brought close to the surface of a substance in a non-contact manner, due to the quantum mechanical tunnel effect,
Charge transfer occurs between the material surface and the electrode needle, and the potential of the electrode needle changes. Moreover, in a single crystal, the electron distribution on the crystal surface is periodic with a period of MA in two directions (X-axis and y-axis directions in the figure) on the surface, depending on the regular arrangement of atoms. By moving the electrode needle parallel to the surface, periodic changes in potential can be detected. By counting the number of these periodic changes, it becomes possible to detect the amount of parallel movement of the electrode needle with ultra-precise accuracy in units of atomic spacing. It has become possible to realize a parallel displacement device.

Example 1 In Figure 0 showing an embodiment of the present invention, 1 is a horizontal needle with an extremely thin tip with a radius of several amps, and 2 is a high-quality single crystal with an extremely smooth surface F. It is a crystal in which one lattice plane of the crystal is exposed, and the lattice spacing of the atoms 3 is known with very high precision, such as Si, Ge, and quartz.

Reference numeral 4 denotes a potential measuring device that detects changes in potential caused by charge flowing into or out of the electrode needle, pulses the change, and counts the change.

As shown in the figure, the atoms 3 of the single crystal 2 are arranged regularly, and the crystal orientation is adjusted so that the arrangement of the atoms 3 on the surface F is parallel to the X and y axes of the parallel displacement device (not shown). It is fixed. The electrode needle 1 is connected to the surface F of this single crystal 2.
When the voltage approaches several amperes, charge movement occurs due to the tunnel effect, and the potential of the electrode needle 1 changes accordingly.
Since the single crystal 2 used in the present invention is a single crystal in which the distance between the lattice planes of the atoms 3 is known, one cycle of the potential change and the electrode needle 1 correspond to the distance between the lattice planes of the single crystal 2. Since this corresponds to the distance traveled, the amount of parallel movement of the horizontal needle can be detected by converting the change in the potential of the electrode needle into pulses and counting them using the high input impedance potential measuring device 4.

By fixing or connecting the electrode needle 1 to a parallel movement device (for example, an xy stage, etc.) that holds the workpiece, the amount of movement of the parallel movement device in the X or both x and y directions can be adjusted with the precision of the crystal lattice spacing. Can be detected.

A specific example is shown in FIG. 2, 4 is the potential measuring device shown in FIG. 1, 5 is a stage for fixing and moving the sample, and 6 is an X-axis drive for moving the stage 5 in the X-axis direction. A device, 7 is a y-axis drive device that moves the stage 5 in the y-axis direction, and 8 is a drive device 6. The drive pulse taken out from 7 is used to calculate the movement ratio of the xMy axes of the base stage 5, and the direction in which the amount of movement is large is calculated. A movement ratio calculation device 9 generates a check signal of about -atomic pitch in synchronization with the drive pulse of the stage 5, and 9 is an atomic unit movement pulse count inputted from the potential measuring device and xy of the stage 5 inputted from the movement ratio calculation device 8. An atomic unit movement calculation device calculates the movement amount of the stage 5 in atomic units based on the axis movement ratio and the check signal, and reference numeral 10 calculates the movement amount in the x and y axis directions in atomic units output from the atomic unit movement calculation device. The display device 11 is a control signal generating device that generates a control signal based on the amount of movement in the xy-axis direction of the atomic unit outputted from the atomic unit movement amount calculating device. With this configuration, when the electrode needle 1 is moved in a straight line as shown in FIG. 3(A), a signal as shown in FIG. 3(B) is detected at the electrode needle 1.

The number of pulses of this detection signal is equal to the movement n < rus of the atomic unit in the direction with the largest movement amount by comparing the movement amounts of the X-axis and the y-axis. The number of pulses obtained by the atomic unit movement calculation device from the potential measuring device 4 is the X-axis.

Which detection signal on the y-axis is detected and the amount of movement in that direction is calculated. The amount of movement in the other direction is calculated from the calculated amount of movement and the movement ratio obtained from the movement ratio calculating device 8. However, in a moving path where the inclination of the moving direction is nearly 45 degrees as indicated by a straight line, there is a possibility that signal pulses twice the normal number will be detected, and in order to prevent this malfunction, the moving ratio calculation device 8 Correction is made by counting only the detection signal superimposed on the check signal of about one atom pitch synchronized with the drive pulse signal in the direction, and the check signal generation operation is cleared and restarted by this detection signal. The measurement signal obtained in this way is displayed on a CRT, printer, etc. by the display device 10, and the M control signal is transferred to the drive device by the control signal generator 11. In this embodiment, the crystal is arbitrarily moved obliquely, but if the crystal is first moved in the X-axis direction and then moved in the y-axis direction, the pulse signal obtained from the potential measuring device 4 It is sufficient to perform calculations while clearing each direction.

Although the above embodiment shows a type in which the electrode needle 1 is moved, the same effect can be expected even if the electrode needle 1 is fixed and the single crystal is fixed to a parallel movement device. According to , it has become possible to realize a device for detecting the amount of movement in a parallel movement device with ultra-precise accuracy of A degree using the atomic spacing of a single crystal as a scale.

[Brief explanation of drawings]

Fig. 1 is a perspective view of an embodiment of the present invention, Fig. 2 is a block diagram of a specific embodiment, Fig. 3 (A) is a diagram of the moving position of the electrode needle, and (B) is detection of the electrode needle. It is a signal diagram.

Claims (1)

[Claims] A single crystal with a known lattice spacing that exposes one lattice plane, fixed to or interlocked with a moving device and moved close to and parallel to the exposed lattice plane of the single crystal. an extremely fine-tipped electrode needle, and a potential measuring device that detects and counts changes in potential caused by charges flowing into and out of the electrode needle when the electrode needle is moved along the lattice plane of the crystal. A parallel movement amount detection device characterized by the following.