JPH0638329B2 - Focused ion beam scanning method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a focus and ion beam apparatus,
The present invention relates to an ion beam mask scanning method.

SUMMARY OF THE INVENTION The present invention is an ion beam scanning method in a focus and ion beam apparatus, wherein when scanning is performed by narrowing the scan area on the mask, the dots on the mask to be scanned are spaced (hereinafter, thinned out). Called)
By irradiating with an ion beam, the charge on the mask is neutralized without increasing the amount of electron beam.

[Conventional technology]

Conventionally, as shown in FIG. 7, the scan area on the mask is divided into 320 dots in both the X and Y directions, and X (orY)
Move 1 dot at a time, irradiate the beam, and
When one line of dots is completed, it is moved by one dot in the Y (or X) direction and is moved again in the X (or Y) direction to irradiate the beam. By repeating this, 320 in the Y (or X) direction
By moving the dots, the irradiation of all dots is completed,
The scan of one frame is completed.

At this time, as shown in FIG. 8, the ion beam is irradiated onto the mask from the ion source 10, and at the same time, the electron beam is adjusted from the electron gun 8 arranged in the vicinity of the ion source according to the irradiation amount of the ion beam. By irradiating, the charge on the mask was neutralized, and the secondary ion was detected by the secondary ion detector 9 to read the pattern on the mask. For example, Japanese Patent Application No. 60-182466 discloses a similar digital scanning method.

[Problems to be solved by the invention]

However, in the conventional scanning method, the number of dots in the scanned area is constant, so if the scan area is narrowed in order to make the pattern reading clear, the irradiation amount of the ion beam per unit area on the mask increases. As a result, the charge neutralization by the electron beam becomes unbalanced, charge-up occurs on the mask, secondary ion detection does not work, and the edge portion of the pattern on the mask cannot be read as shown in FIG. It is inaccurate and unclear. Therefore, in order to balance the charge neutralization, it was necessary to readjust the electron beam to increase it. The disadvantage of the conventional method is that the electron beam amount must be readjusted each time the scan area on the mask is narrowed.

Therefore, the present invention has an object to read a pattern in a narrow area on a mask without compromising the balance of charge neutralization in order to solve such a conventional drawback.

[Means for solving problems]

In order to solve the above problem, the present invention irradiates an ion beam per unit area / time by decimating dots in proportion to the scan area and irradiating and scanning with an ion beam when scanning on a mask. This is a method that enables scanning of a small area without changing the amount and makes it possible to read the details of the pattern on the mask.

[Action]

By performing the scanning method as described above, the charge on the mask is neutralized so that the mask pattern can be read in a wide area, and then, when it is desired to read a part of the pattern in detail, the electron beam can be read. It is possible to read the pattern without re-adjusting the charge neutralization.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 illustrates a thinning scan method when the normal scan area is halved. If the scan area is halved, the area of 1 dot during normal scanning will be irradiated with an ion beam of 4 dots, which is divided into 1/4 of the area of 1 dot during normal scanning. Then, the irradiation sequence of the ion beam is set to 1, 2, 3, 4 and then the first position is irradiated, then moved in the X direction, the dot is removed at the second position, and the next position is irradiated. After repeating one line in the X direction, moving in the Y direction, the dot at the position 3 is removed, and the dot at the next position 1 in the Y direction is again moved in the X direction. Irradiation to position 1 is repeated for one line. When this is repeated until all the dots at the 1 position of Y are completed, the process returns to the first dot and the irradiation of all the dots at the next 2 position is performed in the same manner as the irradiation of the dot at the 1 position. Do the same for dots at positions 3 and 4.

Similarly, when reading the 2 ^{n (n} = 1,2,3,4 ......) content of 1 scan area of, in the same manner for 2 ²ⁿ divided dot positions, 2 X, in the Y direction both ⁿ By repeating the frame scan 2 ²ⁿ times, it can be read.

Although the method of regularly thinning out has been described above, the present invention thins out the ion beam irradiation for the purpose of preventing charge-up on the mask. Therefore, it corresponds to the reduction of the analog scan area. A thinning method is also possible. [Advantages of the Invention] As described above, the present invention, when the mask pattern is read by narrowing the scan area,
Each time the scan area is narrowed, without charge neutralization,
It is possible to read the details of the mask, and the scan of one screen is completed in 1 / ²²ⁿ (n = 1,2,3, ...) of the conventional scan speed. There is an effect that it is possible to quickly search for the pattern.

[Brief description of drawings]

FIG. 1 is a thinned scan display diagram divided into four according to the present invention, FIG. 2 is a thinned scan display diagram divided into 2 ^2n, FIG. 3 is a mask interpretation diagram in a charge-up state,
4 is a sectional view taken along line IV-IV in FIG. 3, FIG. 5 is a plan view of a mask reading in a normal state, FIG. 6 is a sectional view taken along line VI-VI in FIG. 5, and FIG. Beam irradiation scan operation diagram, 8th
The figure is a schematic diagram of ion beam irradiation. 1 …… dot at 1 position 2 …… dot at 2 position 3 …… dot at 3 position 4 …… dot at 4 position 5 …… dot at n position 6 …… cr pattern 7 …… mask 8 ...... Electron gun 10 …… Ion source

Claims (1)

[Claims] 1. A focused ion beam of a focused ion beam processing apparatus is applied to a rectangular area on a surface of a sample at an X dot number in the X direction.
In a focused ion beam scanning method of digitally scanning Y dots in the Y direction, the focused ion beam is scanned on the sample at intervals of one or more X direction dots in the X direction to form one line in the X direction. After the end, the focused ion beam is returned in the Y direction with one or more Y-direction dot intervals in the Y direction, scanned again at the intervals in the X direction, and the scanning is sequentially performed in the rectangular shape. The region is repeatedly scanned, and thereafter, the focused ion beam is scanned from the position adjacent to the first focused ion beam irradiation position in the X direction at the X direction dot intervals, and the focused ion beam is scanned by 1 in the X direction. After the line is completed, the line is returned to the previous position in the X direction with the Y direction dot interval in the Y direction, and again scanned with the X direction dot interval in the X direction, and the scan is sequentially performed. The scanning is repeatedly performed until the intervals arranged in the X direction in the rectangular region are exhausted, and further the above scanning is sequentially performed, and the X direction is the starting position, and each dot having the Y direction dot interval in the Y direction is scanned as a starting point. And irradiating all the dots in the rectangular region on the sample surface with the focused ion beam.