JPS63174323A - Ultrafine processing method using field ionization type reactive gas ion source - Google Patents

Abstract

PURPOSE:To carry out a clean and high-speed maskless ultrafine etching process by ionizing the species of a reactive gas, forming a collected ion beam by the use of an electrostatic lens, and applying that beam to a sample. CONSTITUTION:Applied to a metallic needle 2 of an ion source 1 is the high voltage of a power supply 3 for extraction voltage, and the ion beam extracted through an extraction electrode 4 is radiated toward a sample within an equipment's main body 5. A F2 gas supplied to the ion source 1 is discharged as F<+> or F<+>2 ions, collected by an electrostatic lens 13 through a stigmator lens 12, controlled by a deflecting electrode 14, and radiated onto the Si substrate of a sample 6. With this, a clean and high-speed maskless ultrafine etching is performed.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to ultrafine processing using a focused reactive ion beam;
For example, it relates to a maskless etching method.

[Conventional technology]

Ion sources suitable for forming focused ion beams include liquid metal ion sources and field ion sources.

A liquid metal ion source has a larger energy range of emitted ions than a field ionization gas ion source, making it difficult to form an ultrafine focused ion beam. In addition, in liquid metal ion sources, it is necessary to maintain the emitted ion species in a liquid state, so reactive gases such as F, CQ□, and CF4 are
These ions cannot be emitted from the ion source, so the etching rate can be improved by supplying a reactive gas 22 onto the sample 23 separately from the emitted ion beam 21, as shown in FIG. .

Since this method introduces the reactive gas 22 into the vacuum apparatus, contamination or damage to the apparatus becomes a problem. Additionally, unnecessary ions may be irradiated and cause contamination. Conventionally, field ionization gas ion sources use hydrogen or helium gas to analyze the crystal structure of the needle tip. In addition, although it is possible to generate reactive ions with a duoplasmatron ion source, it is not possible to form a focused ion beam that has low brightness and is suitable for micro-diameter processing with high current density.

[Problem that the invention seeks to solve]

With focused ion beams using conventional methods, there are limits to the types of ions that can be emitted, so it is not possible to freely control the reaction between ions and sample atoms.

The purpose of the present invention is to emit a high-intensity reactive ion beam,
The object of the present invention is to provide a method for performing clean and high-speed ultrafine processing, such as maskless etching, using chemical reactions with sample atoms.

[Means for solving problems]

The present invention uses a field ionization gas ion source to produce F,,Q□.

It is characterized by performing maskless etching using the reactivity of ions by ionizing a reactive gas such as CF, forming a focused ion beam using an electric field lens, and irradiating the beam onto the sample. This is an ultrafine processing method using a field ionization type reactive gas ion source.

[Effect]

Table 1 Table 1 shows the first ionization potential of various simple gases and compound gases. The pressure inside the chamber before gas introduction is 1
It is maintained at an ultra-high vacuum of about 0"-10 Torr. Gas is then supplied to the tip of the emitter needle.

At this time, the pressure inside the chamber is 10-6 to 10-'To
rr.

The area around the differentially pumped emitter chip is 10-4 to 1
It is O-3 Torr. Conventionally, I(2, He gas was used exclusively), but from Table 1, the first ionization potential of these is 15.45 eV for H2 and 24 eV for He.
．． It is 587eV. The ionization potential of F,,CQ,,CF4 is 15.7eV, IL51eV, 1
It has a voltage of 5.35 eV and can be ionized. In this way, H,
, He gas as well as focused ion beam formation using reactive gas ion species such as F, , CQ, , CF, etc. are possible.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 shows the structure of an ultrafine processing apparatus using a field ionization reactive gas ion source.

A high voltage from an extraction voltage power supply 3 is applied to the metal needle 2 of the ion source 1, and the ion beam extracted through the extraction electrode 4 is irradiated toward a sample 6 in the apparatus main body 5. In the figure, 7 is liquid helium and 8 is liquid nitrogen. Ion [1] and the inside of the device main body 5 are each equipped with a vacuum pump 9. l
Degassed at O. A reactive gas 11 is supplied to the ion source 1 . In the examples, fluorine ions will be explained as an example.

The F2 gas 11 supplied to the ion source 1 is Fo or F,
The positive ions are emitted, pass through the astigmatism correction electrode 12, are focused by the electrostatic lens 13, and are irradiated onto the Si substrate of the sample 6 under the control of the deflection electrode 14. 15 is a lens electrode.

FIG. 2 shows the measurement results of the acceleration voltage dependence of the etching rate by ion irradiation. The fluorine ions react with the SL and desorb SiF, which has a high vapor pressure, from the Si substrate.

The etching rate of F" ions increases as the accelerating voltage increases, which is advantageous for obtaining an ion beam with a fine diameter.

〔Effect of the invention〕

As described above, the present invention has the advantage of being able to form a focused ion beam of reactive ions and performing clean, high-speed maskless ultra-fine etching processing.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram showing an embodiment of the ultrafine processing apparatus used in the method of the present invention, Figure 2 is a diagram showing the measurement results of etching of a Si substrate by bio-ions, and Figure 3 is a focused ion beam using the conventional method. FIG. 3 is an explanatory diagram showing an etching rate improvement method using the method. 1...Ion source 6...Sample 11...
Reactive gas 13... Electrostatic lens Figure 1 Ion energy constraint - (KeV) Figure 2

Claims (1)

[Claims] (1) F_2, Cl_2 using a field ionization gas ion source
, CF_4 and other reactive gases are ionized, a focused ion beam is formed using an electric field lens, and the sample is irradiated with the beam, thereby performing maskless etching using the reactivity of the ions. An ultrafine processing method using a field ionization type reactive gas ion source.