JPH02139844A - Beam scanning method using table - Google Patents

Abstract

PURPOSE:To prevent charged-up and flicker on a scanning screen by furnishing a memory table which stores the X-Y beam scanning sequence, forwarding the numerals to a DA converter, and thereupon performing the beam scanning. CONSTITUTION:An arrangement according to the present invention includes a memory table, in which the X-Y beam scanning sequence is stored, and a mechanism to send the numerals read out of this table over to a DA converter, and thereupon a beam scanning is carried out. This beam scanning in any desired sequence allows setting so that the beam irradiation points become discrete one by one within the scanning scope. Therefore, current supply is not concentrated, but can be scattered over the whole scanning scope, which should prevent charged-up phenomenon. Because no boundary exists between the front screen and new screen, possible flicker will be precluded. The beam scanning 4 on the scanning surface is in the sequence as a b c ... i j to then return to (a). After beam scanning, electric charge implatation due to the beam will occur, and accumulation 5 of the charges disappear with time. Because a new scan 4 passes a line discrete, no current supply will be concentrated. Updating of the previous and new screens mixed up should also preclude flicker.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention is a scanning electron microscope, an X-ray mapping device, etc., which scans an electron beam, displays the obtained signal on a CRT, and performs sample observation. The present invention relates to electron beam application devices designed to perform such operations, and particularly to a beam scanning method G in these electron beam application devices.

[Conventional technology]

Beam scanning in electron beam application equipment has been performed using sawtooth wave generators in both the X-axis direction and the Y-axis direction. Therefore, beam scanning was similar to normal TV scanning.

[Problem to be solved by the invention]

Sample observation is performed by irradiating an electron beam, so in places with low conductivity, the electron beam will charge up, causing an abnormal increase in the amount of secondary electrons, causing the image to flicker, or in severe cases, changing the beam trajectory. Since the lens is bent, phenomena such as image distortion occur, which hinders image observation.

In addition, in a device where the beam scanning system and secondary signal detection system are all digitalized, if you try to increase the time per pixel and improve the LS/N ratio, the scanning speed will slow down and the boundary between the previous screen and the new screen will be There was also the problem that the image was visible as flickering, making it difficult to see the image.

[Means to solve the problem]

In order to solve the above problem, the means adopted by the present invention are:
This method includes a memory table storing the XY scanning order of the beam, a mechanism for reading numerical values from the memory table and sending them to a DA converter, and a beam scanning method using the DA converter.

[Effect]

Charge amplification by the electron beam occurs because electrons are supplied in excess of the current carried away by conduction from the beam irradiation point. To prevent this, the current supply should not be concentrated. In the scanning method of the present invention, since the beam can be scanned in any order, the beam irradiation points can be set to be successively scraped points within the scanning range. Therefore, the current supply is not concentrated and can be spread over the entire scanning range, which is useful for preventing charge amplification.

Furthermore, when such a scanning method is used, there is no boundary line between the front surface and the new screen, so flickering is reduced.

〔Example〕 Hereinafter, the present invention will be described in detail with reference to the drawings.

In FIG. 1, 1 is a y-direction scanning table, and this value determines which line is scanned. 2 indicates the scanning order. 3 is a scanning plane. In this example, the X direction is monotonically increasing and the table only scans in the Y direction.

2I21 shows successive changes in the scanning plane in FIG. 1. 4 represents the actual beam scanning, and ta
l−(bl −(cl →[dl −(el −+ (
It is scanned in the order of r) → (gl → fhl → (it → (Jl), and returns to fat again after (J). After the beam scan of 4, charge injection by the beam occurs,
A charge accumulation of 5 remains. This charge accumulation 5 disappears over time (at this time, the new beam scan 4 passes through the cleared line, so the current supply is not concentrated. Also,
Since the previous screen and new screen are updated in a mixed manner, flickering can be prevented.

(Advantages of the Invention) As explained above, by using the present invention, charge-up can be prevented, making it easier to observe samples with low isoelectric constants.Furthermore, flickering on the scanning screen can be prevented. , image observation can be performed comfortably with a longer measurement time per pixel.

[Brief explanation of the drawing]

Figures 1a and b are diagrams explaining the invention in detail, Figure 2 i8
i~('') are drawings showing sequential changes in a scanning plane based on an embodiment of the present invention. ■...Y-direction scanning table 2...Scanning order 3...Scanning surface 4...Beam scanning 5...Charge accumulation Figure 1 (a) (b) (c) (d) Applicant Seiko Electronic Industries Co., Ltd. Representative Patent Attorney Keinosuke Hayashi (f) (h) (i) Figure 2

Claims (2)

[Claims] (1) A beam scanning method using a table, comprising a memory table storing the XY scanning order of the beam, and sending numerical values read from the memory table to the DA converter to perform beam scanning. (2) The beam scanning method using a table according to claim (1), wherein the memory table is limited to only the Y direction and is monotonous in the X direction.