JPH02253548A - Gas ion source and ion beam machining device using it - Google Patents

Abstract

PURPOSE:To heighten resolution so as to prevent an emitter electrode from being eroded by setting the diameter of an opening in the emitter electrode to a given value and cooling it. CONSTITUTION:A gas introduced via a gas introducing tube 3 is ionized in the vicinity of an opening 6a in an emitter electrode 6 and then is used as an ion beam for a machining device via a lead-out electrode 8. A cooling reservoir 2 is formed by a casing body 1 and a wall 2c, and a refrigerant is circulated via an injection port 2a and an exhaust port 2b so that the emitter electrode 6 is cooled to a given temperature, whereby resolution is improved. The diameter of the opening 6a in the emitter electrode 6 is rendered equal to or larger than the diameter of an opening 7a in an insulator 7 arranged to be concentric to the opening 6a. Thus, the emitter electrode is prevented from its exposure to any strong electric field, and therefore there is no erosion of it by such an active gas as water vapor or the like.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is directed to a gas ion source that generates an ion beam by ionizing gas, and a method for forming fine patterns on semiconductor wafers, etc. using the ion beam from the gas ion source. The present invention relates to an ion beam processing device that performs drawing and direct ion implantation.

(Prior art) Gas (e.g. argon, helium, etc.) is used as an ion beam source for ion implantation or fine pattern drawing.
A gas ion source that generates an ion beam by ionizing gas is conventionally known.

FIG. 6 shows a gas ion source according to a first conventional example (Japanese Unexamined Patent Publication No. 57-132654). and a second electrode 103 having a through hole 104 disposed immediately in front of the first electrode at a distance and facing the outlet of the passage 102. Between the first and second electrodes, 5,
A voltage of 000 to 10,0 OOV (7) is applied and the gas exiting from the passage 102 of the first electrode 101 is ionized by the electrons excited by this electric field.

FIG. 7 shows a gas ion source according to a second conventional example (Japanese Unexamined Patent Publication No. 63-174243). , extraction electrode! 07, etc., and a voltage is applied between the porous chip 106 and the extraction electrode 107,
Gas flowing out from the tip of the porous tip 106 is ionized to obtain an ion beam 108. Further, a cooling tank 109 is provided to cool the gas to be introduced, and liquid nitrogen or liquid helium is placed in the cooling tank 109.

Note that the first electrode 101 and the porous tip +06 are collectively referred to as an emitter.

(The problem that IA Ming is trying to solve) In general, the resolution δ of a focused ion beam exposure system (the smaller this value is, the higher the resolution) is given by the following equation (1), ignoring the aberrations of the optical system, and the radius of the ion source. The smaller rt is, the higher the resolution can be obtained.

δ=Mrt...(1) where M
is the magnification of the optical system.

On the other hand, in order to obtain the high resolution required for drawing fine patterns on semiconductor wafers, the diameter of the emitter tip must be approximately 1,000 angstroms (0.1 μm). The diameter of the tip of the first electrode in the conventional example is about 75μ layer, which is not suitable for applications requiring high resolution.Furthermore, in order to obtain a high resolution ion source, It is necessary that the energy distribution of the ions output from the gas ion source in the first conventional example falls within a relatively narrow range as shown by the solid line in Figure 8. As shown in Figure 8, it is estimated to have a spread of about ±10 eV (EO in Fig. 8 is the average energy of the ions), and there is a problem that high resolution cannot be obtained.

In addition, in the second conventional example, the diameter of the tip of the emitter (porous tip 106) is about 1000 to 2000 angstroms, so the required resolution can be obtained, but active gas such as water vapor is present. Then, there is a problem that evaporation of the emitter occurs even at a relatively low electric field strength, and the emitter is eroded.

Furthermore, when the extraction electric field is the same, the lower the temperature of the emitter, the more ion current can be extracted. However, the purpose of the cooling tank 9 in the second conventional example is to cool the gas, and the porous chip 106 (emitter) is not sufficiently cooled.

Therefore, there was still room for reform on this point as well.

The present invention has been made in view of the above points, and is a field ionization type ion source with high resolution (resolution) suitable for applications such as fine pattern drawing and ion implantation, and which also prevents emitter erosion. It is an object of the present invention to provide a gas ion source and an ion beam processing apparatus capable of stably performing high-resolution pattern drawing, ion implantation, etc. over a long period of time.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a gas ion source in which a gas is introduced and the gas is ionized by applying a predetermined voltage between an emitter and an extraction electrode.
The emitter is composed of a metal electrode having a wider opening on the side into which the gas is introduced than the extraction electrode side, and includes an insulator to which the metal electrode is attached, and a cooling means for cooling the metal electrode through the insulator. It was designed to be provided.

Further, it is preferable that the emitter is located on the gas introduction side of the insulator, and that the diameter of the opening on the extraction electrode side is greater than or equal to the diameter of the opening of the insulator.

Furthermore, in order to achieve the above object, the present invention provides an ion beam processing apparatus that includes an ion beam source and processes a workpiece by irradiating the workpiece with an ion beam emitted from the ion beam source. The ion beam source is a gas ion source into which a gas is introduced and ionizes the gas by applying a predetermined voltage between an emitter and an extraction electrode, and the emitter has a side where the gas is introduced is the extraction electrode side. This gas ion source is made up of a metal electrode with a wider opening, and includes an insulator to which the metal electrode is attached, and a cooling means for cooling the metal electrode through the insulator.

(Function) The emitter is effectively cooled, and ions with small energy variations can be obtained. In addition, by setting the diameter of the opening on the extraction electrode side of the emitter to a predetermined value or less,
The variation in ion energy is further reduced. In addition, by providing the emitter on the gas introduction side of the insulator and making the diameter of the opening of the drawer mm larger than the diameter of the opening of the insulator, the emitter will not be exposed to a strong electric field, and the emitter will be exposed to active materials such as water vapor. No longer affected by gas.

(Example) Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of a gas ion source according to a first embodiment of the present invention, in which reference numeral 1 represents a cylindrical housing. The housing l defines a cooling tank 2 for storing a refrigerant (for example, liquid nitrogen, liquid helium, etc.), and the cooling tank 2 is provided with an inlet 2a and an outlet 2b for circulating the refrigerant in the tank. ing.

A shielding member 4 into which a gas introduction pipe 3 is fitted is screwed into the upper opening of the housing l. Further, an insulator 7 having an opening 7a is provided in close contact with the lower part of the cooling tank 2, and the Ji! ! Together with 2c, a gas introduction chamber 5 is defined.

The insulator 7 is made of aluminum oxide (
llz(h), silicon carbide (SiC), aluminum nitride (80N), sapphire, etc. are used. Other than these, synthetic resins such as polyimide, polyamideimide, polyether ether ketone, and polyether sulfide may also be used, and the diameter of the opening 7a of the insulator 7 should be less than or equal to a predetermined value (for example, 1.000 angstroms). .

A metal electrode 6 (for example, tungsten (W), iridium (Ir)) as an emitter is placed on the gas introduction chamber 5 side of the insulator 7.
) etc. are provided, and the metal electrode 6 has an opening 6a corresponding to the opening 7a of the insulator 7. The diameter of this opening 6a is determined by the diameter of the insulator 7 as shown in FIG. 2(a).
The diameter of the opening 7a is equal to or larger than the diameter of the opening 7a. Below the insulator 7, the opening 7
A hole 8a with a diameter of about 1 to 2 IITII is located opposite to a.
An extraction electrode 8 having a diameter is provided with an interval of several degrees or less from the insulator 7.

The lower part of the housing 1 is directly connected to a vacuum chamber such as an ion beam processing device, which will be described later, and is connected to a vacuum chamber of 10-" to 10-" [T
orr].

By applying a voltage (for example, about several tens of kilovolts) that makes the metal electrode 6 side a positive potential between the metal electrode 6 and the extraction electrode 8, the gas is introduced into the gas introduction chamber 5 through the gas introduction pipe 3. Gas (for example, argon, helium, etc.) is ionized near the opening 6a of the metal electrode 6 to become positively charged ions, which are outputted as an ion beam downward in FIG. 1 through the hole 8a of the extraction electrode 8.

The openings 7a and 6a of the insulator 7 and the metal electrode 6 are t, oo
o angstrom or less, and the metal electrode 6 is effectively cooled by the coolant in the cooling tank 2 via the insulator 7, so there is little variation in the energy of the ions.
That is, an ion beam with high resolution can be obtained.

Furthermore, since the diameter of the opening 6a of the metal electrode 6 is greater than the diameter of the opening 7a of the insulator 7, the metal electrode 6 is not exposed to a strong electric field, and even if active gas such as water vapor is present,
There is no corrosion of the electrode due to sputtering or adsorption, and no abnormal discharge occurs.

Further, as shown in FIG. 2(b), the opening 6 of the metal electrode 6
The open end 6b of a is the end surface 7b of the insulator 7 on the extraction electrode 8 side.
Alternatively, it is also desirable that the electrode be raised toward the gas introduction side from the end surface 7b, so that erosion and discharge of the electrode will not occur.

Furthermore, although the metal electrode 6 is shown in a conical shape in FIGS. 1 and 2, it does not necessarily have to be a conical continuous body, and may be divided into several segments.

FIG. 3 is a schematic diagram of a gas ion source according to a second embodiment of the present invention, and this gas ion source is constructed almost the same as that shown in FIG. 1, except for the following points. That is, the gas introduction chamber 5 is defined by the wall 2c of the cooling tank 2;
An insulator 7 is provided in close contact with C. Thereby, the insulator 7 and the metal [t16] can be cooled more effectively.

Figure 4 shows an opening 6a of approximately 1,000 angstroms.
FIG. 3 is a diagram showing an example of a method for manufacturing a metal electrode 6 having the following steps.

The insulator 7' on which the metal film part 6' is formed by sputtering or vapor deposition is eroded into the sodium hydroxide (NaOII) aqueous solution 10, and the voltage between the metal film part 6' and the sodium hydroxide aqueous solution 10 is increased by several V. By applying a voltage of several tens of volts, the surface of the metal film portion 6' is electrolytically polished. Thereby, the aforementioned metal type t16 can be obtained.

Alternatively, as in semiconductor pattern etching, the insulator 7' and metal film part 6' shown in FIG. 4 may be used, and the metal film part 6' may be selectively and repeatedly etched using a shadow mask or the like. .

Furthermore, a conductive material ion different from Si may be implanted into a substrate such as a Si wafer to form a portion different from the base material, and this portion may be selectively etched.

Furthermore, a through hole larger than 1,000 ohms is formed in a substrate such as a Si wafer by beam machining, and after this hole is oxidized and reduced, a conductive material is sprinkled into the hole by sputtering or the like. It's okay.

FIG. 5 is a schematic diagram of an ion beam processing apparatus using the aforementioned gas ion source. In the figure, reference numeral 11 denotes the aforementioned gas ion source, which outputs an ion beam 32. Below the gas ion source 11, a blanker 12, an Einzel lens 13, a deflector 14, and a Faraday cup 15 are arranged in this order. The ion beam 32 is connected to the blanker 1
2. The light is irradiated onto a sample (workpiece, for example, a silicon wafer) 16 on the XY stage 17 through the Einzel lens 13 and the deflector 14, and the sample 16 is processed. Note that the Faraday cup 15 is a detector that can move forward and backward to check the intensity (?!flow value) of the ion beam before processing. Located in a place that does not give

The blanker 12 is a type of deflector, and deflects the ion beam 32 as necessary to prevent the ion beam 32 from passing through the Einzel lens 13, turning the ion beam 32 on (irradiating the sample 16) and off. (interruption). The Einzel lens 13 is an electrostatic lens composed of three 71111s, the top electrode and the bottom electrode are set to zero potential, and the middle electrode is set to a positive potential to focus the ion beam 32. It has the same function as a so-called object aperture. The deflector 14 includes a first electrode 14a and a second electrode 14b,
It is used to adjust the beam imaging position on the sample 16.

The XY stage 17 is a table that can be moved by a stage drive motor 23 in the X-axis and Y-axis directions that are orthogonal to each other, and moves the sample 16 to a predetermined irradiation position. A side length mirror 18 is provided on the XY stage 17, and the length measuring mirror 18 and the laser length measuring device 22
The position of stage 17 is measured with high precision.

Of the above-mentioned components 11-18 are housed in a vacuum chamber 19, and the vacuum chamber 19 is connected to an exhaust device 20.
to a predetermined pressure (for example, 10-” to 10-’ [Tor
rl).

The gas ion source 11 and the Faraday cup 15 are connected to a gas ion source controller 24, which detects and controls the gas pressure of the gas ion source 11, controls the voltage between the emitter and the extraction electrode, Emitter temperature detection, cooling tank coolant supply control, and Faraday cup 15 detects ion current.

Blanka I2, Einzel lens 13, deflector 14,
A blanker controller 25, an Einzel lens voltage controller 26, a beam deflection controller 27, and an exhaust controller 28 are connected to the exhaust device 20, and these controllers 25 to 28 are
Blanka I2, Einzel lens 13, deflector 14,
and the exhaust device 20, respectively.

The laser length measuring device 22 and the stage drive motor 15 are connected to a stage drive device 21, and the stage drive device 21 detects the position of the XY stage 17 and drives it.

Each of the controllers 24 to 28 and the stage driving device 2
1 is connected to a control computer 30 via a CPU interface control circuit 29, and the control computer 30 controls the operation of the entire processing apparatus. Control computer 3
An input/output device 31 is connected to 0, and control data such as irradiation position data and bias voltage is input.

According to the gas ion source II, an ion beam with high resolution (with little chromatic aberration) can be obtained stably over a long period of time, so the above-mentioned processing equipment can stably perform high-resolution pattern drawing, ion implantation, etc. over a long period of time. be able to.

(Effects of the Invention) As detailed above, according to the gas ion source of claim 1 of the present invention, the emitter (metal electrode) is effectively cooled, and an ion beam with high resolution can be obtained. .

Further, according to the gas ion source of the second aspect, since the emitter is not exposed to a strong electric field, it is possible to prevent the emitter from being eroded by sputtering or adsorption even if an active gas such as water vapor is present.

As a result, a stable ion beam can be obtained over a long period of time.

Further, according to the ion beam processing apparatus of the third aspect, processing such as high-resolution pattern drawing and ion implantation can be performed stably over a long period of time.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a gas ion source according to a first embodiment of the present invention, FIG. 2 is an enlarged view of a part of the gas ion source of FIG. 1, and FIG. FIG. 4 is a schematic diagram of the gas ion source according to Example 2, FIG. 4 is a diagram explaining the method of manufacturing the emitter (metal electrode), FIG. FIG. 6 is a schematic diagram of a gas ion source according to the first conventional example, FIG. 7 is a schematic diagram of a gas ion source according to the second conventional example, and FIG. 8 is a diagram showing the energy distribution of ions. 1... Housing, 2... Cooling tank, 3... Gas introduction pipe,
5... Gas introduction chamber, 6... Metal electrode (emitter),
7... Insulator, 8... Extraction electrode. 3 drawings, 4 drawings

Claims (1)

[Claims] 1. In a gas ion source in which a gas is introduced and the gas is ionized by applying a predetermined voltage between an emitter and an extraction electrode, the emitter has an extraction side on the side into which the gas is introduced. A gas ion source comprising a metal electrode having a wider opening than the electrode side, an insulator to which the metal electrode is attached, and a cooling means for cooling the metal electrode through the insulator. 2. The emitter is located on the gas introduction side of the insulator,
2. The gas ion source according to claim 1, wherein the diameter of the opening on the extraction electrode side is greater than or equal to the diameter of the opening in the insulator. 3. In an ion beam processing apparatus that includes an ion beam source and processes a workpiece by irradiating the workpiece with an ion beam emitted from the ion beam source, a gas is introduced into the ion beam source, A gas ion source that ionizes the gas by applying a predetermined voltage between an emitter and an extraction electrode, the emitter comprising a metal electrode with a wider opening on the side into which the gas is introduced than on the extraction electrode side, An ion beam processing apparatus characterized in that it is a gas ion source including an insulator to which the metal electrode is attached, and a cooling means for cooling the metal electrode via the insulator.