JPS59198724A - Formation of insulating film - Google Patents

Abstract

PURPOSE:To enable to form an insulating film in high density, in high purity, and moreover to form in controlled composition by a method wherein the component elements of the insulating film are ionized at every element, and the beams of the ions thereof are irradiated on the surface of a substrate. CONSTITUTION:Ion beam sources 111-113 are provided at the every component element of an insulator to be formed, and a liquid nitrogen shroud 2 to seize unnecessarily evaporated matters and impurity gas molecules is arranged at the circumference thereof. Ionizing cells 3, a substrate 4, a heater 5 and a substrate holder 6, etc. are provided. AT the ion beam sources 111-113, when raw materials are the solids of comparatively low melting points such as aluminum, magnesium, etc., the raw materials are filled up in crucibles manufactured of boron nitride, evaporated according to electric resistance heating of the circumference, evaporated atoms or atomic groups are ionized in the ionizing cells, and accelerated and converged to form an ion beam. Moreover, when the raw materials are the solid materials of high melting points such as silicon, boron, zirconium, etc., the ion beam is formed using evaporation sources according to electron beam heating.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field to which the Invention Pertains] The present invention relates to a method for forming a high-quality insulating film on a substrate, which is required in fields such as the semiconductor industry and the optical component industry.

[Prior art and its problems]

In the semiconductor industry, insulating coatings' (mainly
S t,02, S t3N4, Al2O3, etc.)
As a coating formation method, the CVD method (C
chemical vapor position)
, plasma 7CVD method, sputtering method, etc. have been used. The structure of the coating formed therein is usually amorphous or polycrystalline. Furthermore, it is difficult to control the density, composition, purity, etc. of the film with high precision.

Generally, the density of a film formed by CVD or sputtering is lower than that of a bulk film, lacks density, and has many internal defects. In the CVD method, it is difficult to control the partial pressure of the reactant gas, and in the sputtering method, the deposition efficiency of the target element differs depending on the element, so it is difficult to highly control the composition of the formed film. Furthermore, in CVD and sputtering, the partial pressure of impurity gas inside the equipment is high.
It is difficult to prevent impurities from being mixed into the formed film due to a decrease in the purity of the raw material gas system.

Furthermore, when epitaxially growing a film on a crystalline substrate, it is necessary to heat the substrate to a temperature higher than the so-called epitaxy temperature and to place the attached insulator at a position that matches the crystal lattice points of the substrate. In general, the epitaxy temperature for high melting point insulators is high; if the melting point of the substrate material is low,
It is not possible to raise the substrate temperature beyond this, and epitaxial growth becomes extremely difficult depending on the combination of the substrate and the substance to be deposited. For example, Al on a silicon single crystal substrate.
This is the case when growing 2O, 5i02, etc.

In this case, it is necessary to use special measures to lower the sheathing temperature to a level lower than the melting point of silicon, and this technology has not yet been fully established.

[Purpose of the invention]

The present invention improves the drawbacks of the above-mentioned conventional methods and provides a method by which an insulating film can be formed with high density, high purity, and controlled composition.

[Summary of the invention]

This invention ionizes the constituent elements of the insulating film individually and irradiates the beam onto the substrate surface, thereby causing an insulation breakdown in which the ions react with each other on the surface to form an insulator. This is a method of forming a film.

Here, we prepare an ion beam source for all the constituent elements of the desired insulating film, which can form an insulating film with good characteristics at a low substrate temperature due to the kinetic energy of the ions themselves and the reaction energy of the ions. However, their directions should be directed toward the substrate surface. The ionization is carried out using an ion beam GAL+ using means such as electron bombardment, plasma application, and discharge application.

In addition, in the case of forming an insulating film in the 21°C system, it is possible to control the composition of the film to be formed by using ion beams with different charges and controlling the substrate flow or substrate potential. can.

〔Effect of the invention〕

According to the present invention, it is possible to form an insulating film with high density, high purity, and highly controlled composition, which cannot be obtained using conventional techniques. Furthermore, the formation temperature of the insulating film can be lowered, which contributes to lowering the temperature of the manufacturing process in the half-body industry. In the optical 81S product industry, optical factors such as the refractive index of the coating! It is possible to control the unidirectionality with high precision.

Furthermore, it is possible to easily epitaxially grow an insulating film on a crystalline substrate, which was extremely difficult with conventional techniques.2 [Embodiments of the Invention] Examples of the present invention will be described with reference to the drawings.

The figure is a cross-sectional view of the insulating film forming apparatus used in this example. Ion beam source 1 is used for each constituent element of the insulator to be formed.
11 to 118 are provided, and around them (2 is a liquid nitrogen shroud 2 for capturing unnecessary evaporated matter and impurity gas molecules. 8 is an ionization cell, 4 is a substrate, 5 is a
is a heater, and 6 is a substrate holder.

Ion Beam Red 111 to 113 is used when the raw material is a solid with a relatively low melting point such as aluminum or magnesium.The raw material is filled in a crucible made of boron nitride, and the surrounding area is resistively heated to evaporate the evaporated atoms. Alternatively, atoms are ionized in an ionization chamber, and an ion beam is created by accelerating and converging the atoms using an electric field.

In addition, in the case of high-meltability solid materials such as silicon, boron, and zirconium, an M emission source (sometimes 1
1B-gun) to create an ion beam in the same manner as above.

On the other hand, in the case of gases such as oxygen and nitrogen, the gas is placed in a 3-5 ionization chamber at a pressure of about 10 to 10 Torr, the gas is smeared with high-frequency plasma, and the electric field (
Converge at 7 Jl+ speed from the second.

In this example, zircon (zr2+) ions and oxygen (0-
) using ions, (100) on Si substrate 1:l-
ZrO2 was deposited to a thickness of 500 OA. in this case,
The substrate was electrically suspended and the substrate current was monitored, and the intensity of both ion beams was adjusted so that the current value became zero.

Since Zr+20→ZrO2 is an electrically neutralized process, by controlling the substrate current, it was possible to make the composition of the formed film completely stoichiometric. The density of this film is 5.47 (PAII), and Zr0
It almost coincided with that of t-bulk. Zr3? and the acceleration voltage of the 0-ion beam was 8'00I+'.

For membrane rupture formed at substrate temperature ~700C, Z r 02
The film was epitaxially grown on an F-based (100) Si substrate. The lower limit temperature for epitaxial growth was about 600C. .

It was also possible to form an 8i02 film by using a Si ion beam instead of the 2+ Zr ion beam. In this case, since the reaction of Si + 20-+ Si02 +e is used, a charge is accumulated when 5iO21 molecules are formed.

Therefore, in order to control the film composition, it is necessary to integrate the substrate current and adjust the integrated value to an appropriate value in view of the thickness, area, and density of the film forming the film.

f i di = 1.6 x 10 x S -d
-p (1) Its basic formula is given by formula (1). Here, i is the substrate current, S is the area of the substrate, d is the thickness of the coating, and ρ is the density of the coating (mol e cu I
es/cr/l). Such a control method also applies to the case of forming ZrO2 using monovalent Zr ions Zr+. It is obvious that when monovalent ions and multivalent ions coexist in Zr ions, the effect must be corrected. In that case, each load'
The ratio of tun ions is measured in advance, and the weight of its reciprocal is used to calculate (
1) Use the sum applying the formula. Then, the incident beam intensity may be controlled so that the value becomes constant with respect to the film formation rate.

[Other embodiments of the invention]

Although the above embodiments have described the formation of ZrO2 and 8i02, other j-arnide insulating coatings, such as Al2O, can also be formed.

YO+ Cen2+ Mfi'O, Tie,, V2O,
, Nb2O5, HfO, Ta, 0°, etc., and other nitride insulating films S t3N4 , T IN, AIN, T
The present invention can also be applied to aN, etc.

In addition, although (100) Si was used as the substrate, (111
).

(110), (211), (all) Gc, Gaps of 81 of isogeological surface orientation and various similar surface orientations
, GaP, InP, EnSb, GaxA
Other semicircular substrates such as L, -S and the like may also be used.

[Brief explanation of drawings]

The drawing is a layout diagram of an insulating film forming apparatus used in a method according to an embodiment of the present invention. 111-113...Ion beam source 2...Liquid source, shroud 3...Ionization cell 4...Substrate 5...Heater 6...Substrate holder

Claims (1)

[Claims] A beam of partially or fully ionized atoms or ions corresponding to each constituent element of the desired insulating film is made incident on the substrate to form the insulating film, and at this time, the instantaneous intensity or integral of the current flowing through the substrate is determined. A method for forming an insulating film, characterized by controlling the intensity of each beam so that the intensity is constant.