JPS63208220A - Converged ion beam application - Google Patents

Abstract

PURPOSE:To relieve a charge accumulation effect caused by an ion beam application without reducing the throughput so much by providing an application quiescent period after every beam application of a certain dosage. CONSTITUTION:An application quiescent period is provided after every ion beam 1 application of a certain dosage. If there are a plurality of ion beam applied parts, the respective ion dosages are distributed to a number of times and a plurality of the applied parts are treated in parallel so as to make the individual ion beam applied parts 4-6 have ion application periods and quiescent periods alternately. Further, the ion beam is applied to the applied parts 4-6 from their outline part to the center spirally to provide the application quiescent periods. With this constitution, the charge accumulated during the application period can be naturally made to leak during the quiescent period or the charge can be neutralized by supplying electrons from the outside during the quiescent period. Therefore, a charge accumulation effect caused by the ion beam application can be relieved.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an insulating film using a focused ion beam.

Local etching of a sample covered with a semi-insulating film.

The present invention relates to a focused ion beam irradiation method suitable for deposition.

[Conventional technology]

A focused ion beam device irradiates a desired local portion of a sample with a desired ion species and a desired amount of ions in accordance with various applications such as ion implantation, lithography, and processing. In the conventional ion beam irradiation method, if the sample surface is covered with a film with high insulation (or resistance), the charge irradiated to the sample is difficult to escape, as described in JP-A-58-33837. When the ion beam continues to be irradiated, electric charge accumulates in that area and it becomes electrically charged. As a result, the ion beam is bent just before irradiating the sample, causing the ion beam to be irradiated at the wrong position.Also, if the sample is a semiconductor device, a local discharge phenomenon occurs between the sample surface and the inside of the device, deteriorating the device function. There was a problem that it was easily damaged.

An object of the present invention is to provide a method for alleviating the charge accumulation effect caused by ion irradiation without significantly reducing irradiation efficiency, that is, throughput.

[Means for solving problems]

The above purpose is to set an irradiation pause period for each fixed dose of ion beam irradiation, and if there are multiple ion irradiation sections, the ion irradiation dose of each is divided into multiple times and multiple irradiation sections are processed in parallel. This is achieved by creating alternating periods of ion irradiation and rest in each ion irradiation section. Further, this is achieved by irradiating ions in a spiral shape from the outline of the ion irradiation area toward the center.

[Effect] Allows the charge accumulated during irradiation to leak naturally during downtime,
Alternatively, it becomes possible to neutralize the charge by supplying electrons from the outside.

In addition, by irradiating the beam from the contour of the beam irradiation part, the beam can be irradiated at a precise position without being affected by charge accumulation in the contour, and inside the contour, charge is accumulated in the contour. However, since the ion beam is bent toward the center of the beam irradiation section, the beam irradiation section does not move outward due to the influence of charge accumulation.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. In the present invention, three beam irradiation parts 4 to 6 on the surface of a sample 3 covered with an insulating film are irradiated with a focused ion beam 1. Further, in this embodiment, electrons are supplied by the electron beam 2. The focused ion beam is a 30KeVGa+ beam,
The beam diameter is approximately 0.5 μm, and the beam current is 1 nA. The electron beam is 10-200 eV and the beam current is about 0.5 nA. In this example, each of the three irradiation sections 4 to 6 is irradiated for 60 m5 ec, and each section is irradiated for 60 m5 ec and then stopped for 120 m5 ec.
Ion irradiation was performed 1000 times with a cycle of 8011 seconds. All irradiation times are approximately 3 minutes. The beam irradiation position and irradiation time were controlled using a computer.
According to the present invention, the beam irradiation position shift can be reduced.

Compared to the conventional continuous irradiation method, from ±1μm to ±0
．． This could be improved to about 4 μm.

In addition, when the sample is a silicon element with a high-resistance oxide film (S i Ox ) as a surface film, the conventional method causes about 10% deterioration in element function or damage during deep hole drilling. According to the present invention, it was possible to reduce it to 2% or less.

Although this example deals with the case where electrons were also supplied to the ion irradiation section, the same effect in alleviating charge accumulation was obtained even when electrons were not supplied.

The effect was greater when electrons were also supplied, especially for highly insulating samples.

Next, another embodiment is shown in FIG. In the present invention, a focused ion beam 1 is irradiated onto a beam irradiation section 4 on the surface of a sample 3 covered with an insulating film. The direction 7 of the beam irradiation is
The beam is irradiated from the outline of the beam irradiation unit 4 in a spiral shape toward the center. Beam irradiation was controlled by a computer.

The focused ion beam is a Ga+ beam with an acceleration voltage of 30 K.
V, beam diameter approximately 0.5 μm, and beam current 1 nA. In this example, the beam irradiation section was irradiated for 60 seconds. Conventionally, beam irradiation was performed by rask scanning, but according to the present invention, the positional deviation of beam irradiation could be improved from about ±1 μm to about ±0.4 μm.

Next, still another example will be described. In the present invention, a focused ion beam is irradiated onto a beam irradiated portion of the surface of a sample covered with an insulating film. The beam is 30kV Ga+,
The beam diameter was approximately 0.5 μm, and the beam current was 2 nA. In this example, the beam irradiation and pause times were both 200 m5ec, effectively reducing the beam current to 5
Beam irradiation was performed with the concentration reduced to 0%. According to the present invention, the positional deviation of beam irradiation can be reduced from ±1.5 μm to ±0.4 μm.
was able to improve. However, in the case of this example, the irradiation throughput decreases by about 50%.

〔Effect of the invention〕

According to the present invention, a focused ion beam is connected to an insulating film.

When irradiating a sample covered with a semi-insulating film, it reduces the positional shift of the irradiation beam due to the charge accumulation effect, and if the sample is a semiconductor device, it reduces the deterioration and damage to the device function without significantly reducing the throughput. Therefore, it is effective in highly reliable local etching and deposition of such a sample using a focused ion beam.

[Brief explanation of the drawing]

1 and 2 are perspective views illustrating the focused ion beam irradiation method of the present invention. 1... Focused ion beam, 2... Electron beam, 3.
... Sample, 4 to 6... Beam irradiation section. Figure 1 Figure 2

Claims (1)

[Claims] 1. A method for irradiating a sample covered with an insulating film or a semi-insulating film with a focused ion beam, characterized in that an irradiation pause time is provided for every fixed dose of beam irradiation. Beam irradiation method. 2. The ion irradiation dose of a plurality of local areas on the sample to be ion-irradiated is divided into multiple times, and the ion irradiation is performed on the plurality of local areas in parallel, thereby providing an irradiation pause time. A focused ion beam irradiation method according to claim 1. 3. The focused ion beam irradiation method according to claim 1, characterized in that electrons are also supplied to the ion irradiation part of the sample. 4. A method of irradiating a sample covered with an insulating film or a semi-insulating film with a focused ion beam, characterized by irradiating the irradiated part on the sample with ions in a spiral shape from the outline of the irradiated part towards the center. Focused ion beam irradiation method.