JPS60246546A - Grid for ion beam device - Google Patents

Abstract

PURPOSE:To extract high ion current in a low accelerated voltage by shortly and uniformly keeping the inter-grid distance that accelerates the ions generated from an ion generation chamber. CONSTITUTION:A grid 11 uniformly forms an insulating film 13 made of such as SiO2, Al2O3 on a conductive substrate 12 made of such as an Si single crystal and then a metal thin film 14 made of such as Ti and Cr on it. Then, a hole section 15 for extracting ions in which a great number of holes 151-15n penetrating into a substrate 12 through the insulating film 13 from the metal thin film 14 are perforated is formed between the substrate 12 and the metal thin film 14. In an ion beam etching device, such a grid is arranged between an ion generation chamber A and a neutralizer 7. Ions can be accelerated and extracted from the ion generation chamber by applying preset voltages using the conductive substrate 12 as a screen grid and the metal thin film 14 as an accelerator grid. Besides, the substrate 12 and the metal thin film 14 can be held at an extremely short preset spacing.

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to an ion beam device that performs etching by irradiating a sample with a large-diameter ion generation chamber, and in particular an ion beam device that can draw out a large ion current even at a low acceleration voltage. This concerns the structure of the grid. [Prior Art] FIG. 1 is a schematic diagram of a Kauffman type ion beam etching apparatus which is commonly used as the above-mentioned ion beam apparatus. In the figure, 1 is a thermionic emission cathode supported in the center of the ion generation chamber A, 2 is the same cylindrical anode placed on the circumferential surface of the cathode 1, and 3Vi is installed outside the ion generation chamber A. magnet for plasma generation, 4
1-1 This is a gas introduction port for introducing an inert gas such as argon into the ion generation chamber A. Further, 5 and 6 are grids supported by support members (not shown) outside the ion generation chamber A to accelerate the ions generated by the ion generation member, and 7 is a grid 5 and 6 of these grids. This is a neutralizer (also called a neutralizing electrode) for converting the extracted ions, so that these ions are irradiated onto the material to be etched 9 placed on the sample stage 8 in the test*+UB. Here, when thermoelectrons are emitted from the cathode 1 while a magnetic field is generated by the plasma generating magnet 3, the thermoelectrons start a cyclo)on motion. Then, when an inert gas such as argon is introduced from the gas inlet 4 with a potential applied to the anode 2, the inert gas flows to the cathode 1.
The plasma is turned into plasma by the bombardment of thermionic electrons, and this plasma is distributed within the ion generation chamber A and extracted by grids 5 and 6 located outside the ion generation chamber A. At this time, grid 5.6
As shown in the cross section of Figure 2, two conductive disks with many holes (usually 5 or less in size) are placed facing each other at a certain distance so that the holes are aligned. The grid facing the plasma is called a screen grid (5), and the grid facing the material to be etched 9 is called an accelerator grid (6). Therefore, the accelerator grid 6 has a negative potential, and each electrode of the twisted screen grid 5, anode 2, and cathode 1 has a positive potential.

[
When the first order is added, ions generated from the ion generation chamber A are accelerated between the two grids 5 and 6 and collide with the material to be etched 9, causing etching by a sputtering phenomenon. In this case, the ion current density j drawn from each grid 5, 6 is given by Child's law shown below. j = (4t 6 /9) (2e 7m)”2
V3A/L However, eo''゛Dielectric constant of the intergrid medium - Ratio of charge and mass of ions■Nigerid potential difference tNigerid spacing From the above formula, in order to increase the ion current density, the spacing between grids 5 and 6. However, if the distance between the grids 5 and 6 is made small, it becomes difficult to keep the distance equal and constant over the entire surface of the grid due to deformation that occurs during processing. Contact between the grids 5 and 6 becomes difficult due to thermal deformation in the grid. Therefore, the distance between the grids cannot be made very small, and it is difficult to obtain a large ion current value with the conventional grid structure. In particular, the ion beam apparatus can be used as a dry etching apparatus as shown in FIG. Although it is often used as a film device, it has the drawback that the etching rate and film formation rate are slow because a large ion current value cannot be obtained. The purpose of this is to keep the distance between the grids that accelerate the ions generated from the ion generation chamber short and uniform, thereby creating an ion beam device that can draw a large ion current even at low acceleration voltages. To achieve this objective, the present invention provides a conductive substrate, a metal thin film deposited on the substrate with an insulating film interposed therebetween, and a metal thin film formed on the metal thin film. and a hole portion for ion extraction in which a hole is selectively formed between one metal thin film and the other substrate by separating the separate insulating film from the other substrate, and the metal thin film is used as a first grid. By using the substrate as a second grid and applying a predetermined potential to these grids, the entire ion beam generated from the ion beam generation chamber is accelerated and extracted.Hereinafter, embodiments of the present invention will be described. will be explained in detail with reference to the drawings. [Embodiment] Fig. 3 is a cross-sectional view of a main part of a grid for an ion beam device according to an embodiment of the present invention, and the grid 11 of this embodiment is
is Si02 on a conductive substrate 12 such as S1 single crystal.
An insulating film 13 made of rAtz O3 or the like is formed uniformly, and Tl, C is formed on this insulating film 13. A large number of holes 151 to 15n are selectively formed between the substrate 12 and the metal thin film 14 to penetrate through the metal Wf, the film 14 and the insulating film 13 to the substrate 12. A drawer hole 15 is formed. The grid created in this way can be produced using, for example, the ion beam etching apparatus fJ! shown in FIG. When applying tK, it is placed between the ion generation chamber A and the neutralizer 7, and the conductive substrate 12 is used as a screen grid, and the metal thin film 14 is used as an accelerator grid, and by applying a predetermined potential to each, ions are generated. Ions from the generation chamber can be accelerated and extracted. Therefore, the grid structure of the above embodiment can be created using RF sputtering method etc. on the substrate 12 up to an area of about 5 inches in diameter.
The insulating film 13t, such as Oz + Atz 03, can be uniformly formed to a thickness of about 50 μm. Therefore, since the substrate 12 and the metal thin film 14 are held at a very short constant interval, a large ion current can be obtained even at low voltage. Further, even if the substrate 12 is heated or deformed, the two grids will not come into contact with each other as in the conventional case, so the operation 75-
X will not be damaged. Furthermore, the breakdown voltage characteristic of Si02 as the insulating film 13 ranges from 20 to 40'v/WrM, so even if the thickness of this insulating film is 50 μm,
An accelerating voltage of KV can be applied, which has the effect of being able to obtain Taisho and current over a wide range of accelerating voltages. Note that it is clear from the above description that similar effects can be obtained even when the conductive substrate 12 is used as an accelerator grid and the metal thin film 14 is used as a screen grid in the grid structure of the above embodiment. FIG. 4 shows an example of the manufacturing process when an S1 single crystal having a specific resistance of 1 to 2×10 Ω·- is used as the conductive substrate 12. In the figure, first, a 5102 film 13 is formed as an insulating film on the surface of a Si single crystal substrate 12 to a predetermined thickness by means such as sputtering. At this time, the surface of the S1 single crystal substrate 12 is thermally oxidized to
The entire 02 film may be formed. After that, 5102 membrane 13,
A metal thin film 14 such as T1, which can be selectively etched with respect to the Si single crystal substrate 12, is formed on the 5102 film 13 (
Figure 4(a)). Next, the gold-striped thin film 14 is etched into a predetermined pattern using a conventional first printing technique to selectively form holes 153 to 15n (only 151 and 152 in the figure) (FIG. 4(b)). Next, make this gold 184Nm 14k mask and make it 510
2 film 13 and the S+IIl crystal substrate 12 are etched (FIG. 4(C)). At this time, a buffered hydrofluoric acid solution is often used for wet etching of the 5IOzleN 13, but if the amount of etching is large, side etching of the SiO2 film 13 is large, making microfabrication difficult. Also, there is no suitable metal thin film to act as a mask for the buffered hydrofluoric acid solution. Therefore, the 5102 film 13 can also be etched by ion beam etching using a CF-based gas. This CF
5102 film 13 by 4 gas ion beam etching
FIG. 5 shows the etching speed. Figure 5 shows the etching conditions: /Jl + speed voltage IKV, current density 1mh/e
The case of ra is shown, and the symbol I is 5i0 for the operating vacuum degree.
2 shows the etching rate of the 2 film 13, and the symbol 1I also shows the etching rate of TI+Cr as the metal thin film 14. As is clear from the figure, 5iOzDJ
The etching rate ratio of l3 and Tl, Cr thin film is lX
Since it becomes 6 or more at l0 Torr or more, the number 10
Processing with less side etching can be performed even on 5 iOz HKI 3 with a thickness of μm. Primary, Ti,
Since the thin film C is not etched by the etching solution for the S1 single crystal substrate 12 which will be described later, it can be used as a grid even after the S1 single crystal substrate is etched. After etching the 5i02 film 13, this 5i02 film 13 is etched.
Ethylenediamine as a 10z membrane't mask. Si single crystal substrate 1 with a mixture of pyrocatechol and water
Etch 2. As is well known, in the above etching solution, <100> at 00°C. The etching rate ratio of <110> and (11D crystal axis directions is 50:30:3 μm/hr. Therefore, if a substrate in which the two vertical directions of the two surfaces are oriented in the <100> direction is used, the vertical direction of the surfaces is of about 35.3° to
Further, when a substrate oriented in the <110> direction is used, selective etching proceeds at an angle of approximately 0°, and an ion extraction hole 15 consisting of small side-etched holes 151 to 15n is obtained. As for the 2jI% substrate, in the case of a GaAl1 single crystal substrate, the same processing as in the case of the Sl crystal can be performed by etching the (100) oriented substrate with a solution consisting of hydrochloric acid, hydrogen peroxide, and water. I can do it. 1. A thin metal plate such as stainless steel can also be used. In addition, although the above-mentioned embodiment shows a case in which a metal film is formed on one side of a conductive substrate via an insulating film, the present invention is not limited to this, and the present invention is not limited to this. By forming a metal R pattern through the insulation m and providing holes for ion extraction similar to those in Example 1 above, these substrates and the Kanamaki i1Q film were each used as a grid ↑
,'·)hv. Furthermore, the metal thin film
The structure is not limited to a medium layer of Tj or Cr, but can also be made of a trr layer ↑j·1゛ made of silk of these metals. [Effects of the Invention] As explained above, according to the present invention, the distance between the grids that accelerate the ions generated from the ion generation chamber can be kept short and uniform, so that the distance between the grids that accelerate the ions generated from the ion generation chamber can be kept short and uniform.・A large current can be obtained with the surrounding acceleration box and pressure, so it can be used in an etching device to increase the etching rate, and it can also be used in an ion beam sputtering deposition device to increase the deposition rate. There are other effects.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a commonly known Kauffman type ion beam etching apparatus, FIG. 2 is a schematic sectional view of the grid shown in FIG. The figure is a manufacturing process diagram of an embodiment of the present invention, and FIG.
FIG. 3 is a characteristic diagram showing the relationship between the cutting/cutting speed and the operating vacuum degree of Tr and CrM. A: Ion generation chamber, B: To the sample, 1...
・Cathode, 2--Anode, 3--Magnet, 4--Gas introduction [ko, 5--Screen grid, 6--Monk accelerator grid, 7--
Fist neutralizer, 8... Sample stand, 9... Material to be etched, 12-... Conductive substrate (screen grid), 13... Insulating layer, 14... Metal 'A'
9 (accelerator grid), 15... hole for ion extraction. Patent Applicant Nippon Telegraph and Telephone Public Corporation Agent Masaki Yamakawa (and 1 other person) Figure 1 Figure 2 Figure 3 City Figure 4

Claims (1)

[Claims] A conductive substrate, a metal thin film deposited on the substrate via an insulating film, and a hole between the metal thin film and the substrate through which the metal thin film passes from one metal thin film to the other substrate through the insulating film. 1. A grid for an ion beam device, comprising selectively formed holes for extracting ions.