JPH03110741A - Processing method for single sheet type grid for ion gun - Google Patents

Abstract

PURPOSE:To make it possible to obtain high current density at low accelerating voltage by finishing both surfaces of a grid by means of electro-polishing, ion radiation, sand-blasting, laser beam radiation and the like. CONSTITUTION:In the final processing for manufacturing a single sheet type grid which is used for a type of an ion gun for extracting lean gas ion from plasma, whereas it is mainly used in two ways, that is, for acceleration of ions and for extraction of ions, both surfaces of the grid is finished by means of electro-finishing, ion radiation, sand-blasting, laser beam radiation and the like. Burrs can thereby be removed. By this constitution, ion current density obtained from etched surfaces can thereby be made higher as compared with a case where the single sheet type grid the surface of which is not processed by means of surface finish as described above is used in an ion gun.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for processing a single-piece grid of an ion gun used in an ion beam sputtering device or an ion beam etching device used in semiconductor manufacturing, etc. It is.

(Prior art) Ion beam sputtering equipment and ion etching equipment, which have become widely used in recent years to create fine pattern shapes and magnetic films, generate inert gas ions and accelerate them. An ion gun is required to create an ion beam that collides with the target or object to be etched. Furthermore, recently, low energy ion guns have been developed and used which are extremely effective in avoiding damage to the object to be etched and improving the properties of amorphous materials, especially in the production of magnetic films. However, the two-piece grid normally used for ion guns cannot obtain a sufficient ion current density at low energy, that is, low acceleration voltage, and it takes a long time to process the object to be etched. It was not possible to increase the deposition rate and it took a long time to form a film.

In order to avoid this, as previously disclosed in JP-A-63-124343, the hole diameter is 0.21 to 0.4s+.
By using a single grid with many m pores, it is possible to obtain a greater ion current density than when using a two-plate grid, reducing the etching time and film formation time. I was able to figure it out.

The details will be explained using a Kaufmann type ion gun as a typical example of the type 2 ion gun. FIG. 2 shows a conventional ion etching apparatus. In the figure, 1 is a Kauffman type ion gun, and the ion gun 1 is installed on the right side of the etching chamber 2. As shown in FIG. The etching chamber 2 is provided with an exhaust port 3 connected to an exhaust system (not shown).
After the inside of the ion gun 1 is sufficiently evacuated, an inert gas such as argon gas is introduced from the gas inlet 5 provided in the case portion 4 to create a dilute gas state with a gas pressure of about 0.111 mTOrr. The ion gas 1 is provided with a cathode 6 for emitting thermionic electrons and an anode 7 corresponding to the cathode 6. Further, an electromagnet 8 is disposed on the outer side of the case portion 4 for causing the thermoelectrons emitted from the cathode 6 to spirally move. The cathode 6 and the anode 7 constitute a discharge means, and the discharge means and the electromagnet 8 generate plasma in a dilute argon gas state.
ions are generated.

On the front side of the ion gun 1, that is, on the etching chamber 2 side, - extractor grids 9 for extracting ions are provided.
will be placed. A negative potential is applied to the cathode 6 by a power source 12 to this half-shaped grid 9, which has the function of accelerating positive ions in the generated plasma and drawing the ions into the etching chamber 2. Further, 10 is a cathode power supply, 11 is an anode power supply, 12 is an acceleration power supply, and 13 is an extractor power supply. Note that a power source for driving the electromagnet 8 is not shown here.

With the configuration of the ion gun as described above, the extracted argon ions strike the object to be etched 14 and physically etch it. In the case of ion beam sputtering, 14
serves as a target, and particles sputtered here are deposited on the substrate 15.

(Problem to be Solved by the Invention) A one-piece grid is usually made of stainless steel, such as 5US304 or molybdenum plate, with a thickness of 1 cm or less.
．． Pores with a diameter of 2m+g to 0.4mm with an aperture ratio of 50
% or more, a mask is formed on both sides, a chemical etching solution is sprayed on both sides, and pores are bored from both sides. These pores must penetrate from both sides of the plate to the opposite side perpendicular to the plate surface, but due to the characteristics of etching, it is inevitable that the pore diameter will be slightly smaller in the center of the plate. During this etching, minute paris are formed at the edges of the pores, which can barely be seen under a microscope with a magnification of approximately 500 times.These paris prevent the beam from moving in a straight line when the ion beam is extracted. In section 14, a beam of less than half the current density could normally be obtained. It has also been found that the particles of such a sheet-shaped grid are removed by being hit by ions on the plasma side several times, and that the original current density can be obtained by turning the grid upside down. It has also been found that among many grids, original current densities can be obtained if the chemical etching conditions happen to be such that Paris is difficult to form. However, from an industrial perspective, it is necessary to always provide a single-piece grid that guarantees a normal current density without sparks.

The present invention was proposed in order to improve the above-mentioned drawbacks, and an object of the present invention is to provide a method for processing a single-piece grid that can obtain a high current density at a low accelerating voltage.

(Means for Solving the Problems) In order to achieve the above object, the present invention generates plasma in a diluted gas state and is used in an ion gun that extracts diluted gas ions from it, and is used for two main ion acceleration and ion gun applications. A one-piece grid used for drawers,
The gist of the invention is a method of processing a single-piece grid for an ion gun, which comprises finishing the surfaces of both sides of the grid by electrolytic polishing, ion irradiation, sandblasting, laser beam irradiation, etc.

(Function) In the present invention, - In the final manufacturing process of the sheet-shaped grid, pars can be removed by finishing the surfaces of both sides of the grid by electrolytic polishing, ion irradiation, sandblasting, laser beam irradiation, etc. So,
The ion current density obtained at the surface of the object to be etched can be increased compared to the case where a conventional one-piece grid without surface finishing is used in an ion gun.

(Example) Next, an example of the present invention will be described. It should be noted that the examples are merely illustrative, and within the scope of the spirit of the present invention,
It goes without saying that various changes and improvements can be made.

Examples of the present invention will be described below with reference to a Kaufmann type ion gun with a grid diameter of 10 cm.

As shown in the steps in FIG. 1, one grid was first prepared as follows.

Stainless steel (SUS 30) is used as the substrate material for the grid.
4) Using a plate with a thickness of 0.2+*m, degrease it.

After pre-treatment such as pickling, washing with water, drying, resist mask patterning from both sides of the plate, i.e. applying resist, developing, washing with water and drying, then spraying etching solution on both sides, washing with water and drying. Hole pitch 0.35+*m
A grid with a pore diameter of 0.3+*m and an open area ratio of 57% was prepared. This is a traditional grid.

This unfinished grid was designated as A, and was subjected to various finishing processes that are the characteristics of the present invention.

First, 56 ml of phosphoric acid. The electrolyte is 44 parts water and 1 part water is used, a stainless steel plate (SUS304) is used as the cathode, and the temperature is 20°C1.
Grid B was electrolytically polished for 20 seconds using unfinished grid A as an anode at a voltage of 2 V and a current density of 10 mA/cm".
Next, the unfinished grid A was heated with a machining fluid of #120 diamond sand and water at a pressure of 3 atm for 50 cm.
Grid C is the result of sandblasting by spraying from a distance of m for 30 seconds. Further, under the ion etching conditions shown in Table 1, unfinished grid A was placed as an object to be etched, and grid D was etched by ion irradiation for 1 minute.

Table 2 shows the current density at the etched portion when each of the grids thus produced was used as a one-piece grid in FIG. 2 and etched under the etching conditions shown in Table 1.

1 Distance from ion beam etching grid to object to be etched: 25cm Argon gas pressure: 0.2m+■↑
orr acceleration voltage 200
v Anode power supply voltage 60V Extractor power supply voltage -40V Current measurement area for determining the ion current density on the object to be etched 80m-φ (50cm
1g) Angle between the surface of the object to be etched and the ion beam 45
゜Anode current 300■ when determining ion current density
A2 Ion grid A (
Conventional product) 0.9■^/cs+” Grid B (electrolytic polishing)
2.1mA/cm" Grid C (sandblasting) 2.3mA/CI8 Grid D (ion irradiation) 2.2mA/cm" As is clear from the results in Table 2, compared with the unfinished conventional product (Grid A) death,
It is recognized that the current density of grids B, C, and D, in which grid A is subjected to electrolytic polishing, sandblasting, and ion irradiation as in the present invention, is more than twice as high as that of the conventional product.

This is considered to be because "burrs" can be removed by applying the processing of the present invention to the grid surface, and as a result, the directionality of the beam becomes uniform.

Incidentally, in addition to the processing described above, the same effect can be produced by irradiating with a laser beam.

(Effects of the Invention) According to the present invention as described above, - In the final step of manufacturing the patterned grid, the surfaces of both surfaces of the grid are subjected to electropolishing, ion irradiation, sandblasting, laser beam irradiation, etc. As a result, it is possible to obtain an ion current density that is more than twice as high as when using a conventional unfinished grid as a single-piece grid for low-energy ion beam extraction, and therefore, the etching efficiency is improved. It has a significant improvement effect.

[Brief explanation of drawings]

FIG. 1 is a process diagram of a grid processing method according to the present invention, and FIG. 2 shows a conventional ion beam etching apparatus. 1... Ion gun 2... Etching chamber 3... Exhaust port 4... Case part 5... Gas inlet 6... Cathode 7... ... Anode 8 ... Electromagnet 9 ... Grid 10 ... Cathode power supply 11 ... Anode power supply 12 ... Acceleration power supply 13 ... Extractor Power supply 14...Object to be etched 15...Substrate

Claims (1)

[Claims] This is a one-piece grid used in an ion gun that generates plasma in a diluted gas state and extracts diluted gas ions from it, and is used for two main purposes: ion acceleration and ion extraction, and both sides of the grid are electrolytically polished. A method for processing a single-piece grid for an ion gun, characterized by finishing the surface by ion irradiation, sandblasting, laser beam irradiation, etc.