JPH0471154A - Linear electron beam emission method - Google Patents

Abstract

PURPOSE:To uniformize the quantity of linear electron beams emitted all over a sample by differentiating the beam profile of each of the linear electron beams having measured with a Faraday gauge having its incident beam stop formed in the shape of a slit, and then equalizing the width of a beam waveform corresponding to the maximum value and minimum value of the differentiation result data to a width for making a step movement in a direction orthogonal to a beam-scanned direction. CONSTITUTION:Linear electron beams l are scanned vertically to an incident beam stop in the shape of a slit, and then each of beam currents passing through the incident beam stop is measured as a voltage generated in a detecting resistance 4 by a monitor 5 having a beam current-differentiating function, so that the value of the beam current can be measured. Because the incident beam stop is in the shape of a slit, the beam currents measured form a unidimensional current distribution in a linear direction integrated in the slit direction of the incident beam stop. The maximum value and minimum value of the measurement result data are each located at about half the value of each of the linear beams. The space between the maximum value and the minimum value can be accordingly equalized to a width for making a step movement so as to uniformize the total quantity of emitted beams. When the return of a beam emission method to its initial position at the time of repeating the method is shifted by half the step-moved width, positions of emitted beams may be alternated with one another to heighten uniformity in the quantity of the emitted beams.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is directed to a linear electron beam device used in a source linear electron beam device used for etching, film formation, annealing of semiconductors such as silicon, or welding and processing of mechanical parts. This relates to a beam irradiation method.

[Conventional technology]

Faraday cages are usually used to measure beam systems of charged beams such as electrons and ions, and various shapes are used depending on the purpose, such as measuring beam current and beam current distribution (edited by the 132nd Committee of the Japan Society for the Promotion of Science). :Electron/Ion Beam Handbook 2nd edition (Nikkan Kogyo Shimbunsha (1986)
), P, 269 >.

In addition, the scanning method of the beam depends on the application, such as a scanning electronic microscope that scans in the same way as a television (edited by the 132nd Committee of the Japan Society for the Promotion of Science: Electron and Ion Beam Handbook 2nd Edition (Nikkan Kogyo Shimbun (1986) ), P.
617), something that performs mask scanning or vector scanning like a drawing device. Edited by the 132nd Committee of the Japan Society for the Promotion of Science: Electronics.
Ion Beam Handbook 2nd Edition (Nikkan Kogyo Shimbunsha <1
986) ), P, 429), Japanese Patent Laid-Open No. 62-213, which uses a mask to scan the beam irradiation area to match the width of the semiconductor chip, as in an electron beam annealing device.
055), Nikkan Kogyo Shimbunsha (1986)), which uses various methods to scan the sample like an ion implanter.
, P, 590).

[Problem to be solved by the invention]

However, when uniformly irradiating a sample with a linear electron beam, there is no established method due to the special characteristics of a linear beam.When irradiating a large area wider than a linear beam, beam scanning It becomes necessary to irradiate the beam while moving the position in steps. At this time, the amount of beam irradiation in the overlapping portion of the beams must be the same as that in other portions. In conventional beam-based measurement methods, the operator looks at the current distribution and inputs the step movement width so that the beam irradiation amount in this overlapping area is the same as in other areas, or the beam irradiation amount due to overlapping is determined by image processing. The amount had to be calculated and the setting method was complicated.

An object of the present invention is to eliminate such conventional problems, determine the beam step movement width in a simple method, and
An object of the present invention is to provide a linear electron beam irradiation method that uniformly irradiates a linear beam.

[Means to solve the problem]

According to the present invention, the beam profile of a linear electron beam measured with a Faraday cage having a slit-shaped entrance aperture is differentiated, and the width of the beam waveform corresponding to the maximum and minimum values is calculated perpendicular to the beam scanning direction. The beam scanning position or
is a linear electron beam irradiation method in which the sample is moved sequentially relative to each other, the entire surface of the sample or a required area is irradiated with the beam, and this is repeated as necessary, or the beam scanning position or the relative By repeatedly moving the sample sequentially, irradiating the entire surface of the sample or the required area with the beam, returning to a position shifted by half the beam deflection width from the initial position, irradiating the beam sequentially, and returning to the initial position again. After irradiating the entire surface of the sample or the required area with the beam using the linear electron beam irradiation method that irradiates the required amount of beam, or the method described above, rotate the sample 90 degrees, irradiate the beam again in this direction, and reposition the sample as necessary. A linear electron beam irradiation method according to claim 1 or 2 is obtained, in which a required amount of beam irradiation is performed by repeating the beam irradiation by rotating 90 degrees.

〔Example〕

Next, an embodiment of the present invention will be described with reference to FIG. 1 and FIG. 5.

FIG. 1 shows a one-dimensional current distribution of a linear beam and its differential shape measured by a heam entrance aperture 6 or a slit-shaped Faraday cage 3 as shown in FIG. The linear electron beam 1 shown in FIG. 5 scans perpendicularly to a slit-shaped beam entrance aperture, and the beam current passing through the entrance aperture is measured as a voltage generated in a detection resistor 4 by a monitor 5 having a differential function. . By monitoring the voltage generated across this detection resistor, the beam current value can be measured. If you draw a graph where the vertical axis is the beam current (voltage generated in the detection resistor) and the horizontal axis is time, you can draw a diagram like the one in the top row of the first country. If the scanning speed of the beam is known in advance, the time on the horizontal axis can also be used as position. When the waveform of the beam current distribution obtained in this way is differentiated, it becomes as shown in the lower part of FIG. 1. Furthermore, since the incidence aperture is slit-shaped, the measured beam current has a one-dimensional current distribution in the linear direction integrated in the slit direction.

Processing of samples through chemical reactions such as etching and film formation is
If the energy of the irradiated electrons is greater than the activation energy that causes a chemical reaction, the amount of processing is proportional to the amount of irradiated electrons. Monitoring the amount of electrons irradiated by scanning a linear beam means monitoring the integral value of the beam current with respect to the scanning direction. The integral of the beam current with respect to the scanning direction is the same as the beam current distribution measured with a Faraday gauge using a slit-shaped entrance aperture. If the linear beam can irradiate the entire surface of the sample or the required area at once, the beam irradiation amount will be uniform if the beam is uniform. It must be divided into different areas. That is, step movement is performed perpendicular to the scanning direction of the beam, and the scanning and step movement of the beam are sequentially repeated to irradiate a large area with the beam. As the step movement, there are a method in which the beam position is moved by electromagnetic deflection, and a method in which the beam scanning position is the same but the position of the sample 2 is moved. As shown in the figure, the beam step movement direction and the sample step movement direction are opposite so that the beam scanning position moves relative to the sample. Beam scanning can be done by scanning the beam in both directions at the same speed on both going and returning (beam scanning direction ■ in the figure), and by making extreme differences in the going and returning speeds, which hardly affects the beam irradiation on the way back. to be free of
There is a method of always setting the beam in the same direction (beam scanning direction (■) in the figure). Further, depending on the need, it may be necessary to irradiate the beam only to discrete positions, and the beam can be moved to the required area by high-speed scanning of the beam (not shown). When beam irradiation is performed in divided beams, in order to irradiate the entire surface of the sample uniformly, the total beam irradiation amount in the overlapping portion of the beam must be the same as that in other portions. If the sloped parts at both ends of the linear beam are symmetrical, if the part corresponding to half the beam current of the sloped part is detected and this is defined as the overlapping part of the beam, the total difference between the other parts and the beam as shown in Figure 2 is The irradiation amount will be the same. As shown in FIG. 1, the integral shape of a linear beam is close to a positive and negative Gaussian distribution at the ends of the beam. Moreover, its maximum and minimum values are located approximately at half of the linear beam.

Therefore, by setting this interval as the step movement width, the total beam irradiation amount can be made uniform.

Figure 3 shows a method of overlapping the beams and the total beam irradiation amount, which is different from that shown in Figure 2, using the step movement width determined using the method shown in Figure 1. This is a method in which the return to the initial position when repeating the irradiation method is shifted by half the step movement width. With this, when repeatedly irradiating the beam, the irradiation position is alternated between odd and even times, improving uniformity.

Furthermore, in addition to the beam irradiation method shown in Figures 2 and 3, the sample may be rotated 90 degrees during repeated beam irradiation to intersect the beam scanning direction to improve uniformity (not shown). ).

〔Effect of the invention〕

As explained above, the method for determining step movement width of a linear electron beam according to the present invention makes it possible to make the irradiation amount of the linear electron beam uniform over the entire sample. A membrane etc. can be applied.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the concept of the step movement width determination method of a linear electron beam according to the present invention, FIG. 2 is a diagram showing an example of step movement of a linear electron beam, and FIG. 3 is a diagram showing a linear electron beam step movement width determination method. FIG. 4 is a diagram showing the concept of a linear electron beam scanning method, and FIG. 5 is a diagram showing the concept of linear electron beam current measurement. 1... Linear electron beam, 2... Sample, 3... Faraday cage, 4... Detection resistor, 5... Monitor
6...Beam entrance aperture.

Claims (1)

[Claims] 1. Differentiate the beam profile of a linear electron beam measured with a Faraday cage with a slit-shaped entrance aperture, and calculate the width of the beam waveform corresponding to its maximum and minimum values with respect to the beam scanning direction. A linear electron beam irradiation method in which the sample is sequentially moved to the beam scanning position or relative to the sample in the step movement width, and the entire surface of the sample or a required area is irradiated with the beam, and this is repeated as necessary. Method. 2. Sequentially move the sample at the beam scanning position or relative to each other with the step movement width determined by the method described in claim 1, and after irradiating the entire surface of the sample or a necessary area with the beam, shift the length by half the beam deflection width from the initial position. A linear electron beam irradiation method that irradiates the required amount of beam by repeating the steps of returning to the original position, irradiating the beam in sequence, and returning to the initial position again. 3. After irradiating the entire surface of the sample or the required area with the beam, rotate the sample 90 degrees, irradiate the beam again in this direction, and repeat the process of rotating the sample 90 degrees and irradiating the beam again as necessary to achieve the required amount of beam irradiation. Claim 1
Or the linear electron beam irradiation method according to 2.