JPH08259400A - Diamond etching method and apparatus - Google Patents

Abstract

(57) [Summary] [Purpose] By irradiating diamond with a particle mass composed of accelerated multiple molecules or atoms as constituent particles in a reduced pressure atmosphere, the diamond can be easily and efficiently etched without damaging it. A method and apparatus for performing the method are provided. [Constitution] Particle mass generation (4), ionization (5), mass separation
Particle mass 1 generated through steps such as (6) and acceleration (7) is
The diamond layer 2 is irradiated with a predetermined energy in the irradiation step (8). When the irradiated particle mass 1 collides with the diamond layer 2, it decomposes into individual molecules or atoms, changes its momentum (direction / speed) and energy, and sputters the surface layer of diamond. As a result, diamond is efficiently etched and the etched surface becomes smooth. The diamond layer 2 is masked with a mask material 3 such as silicon dioxide.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for industrially etching diamond.

[0002]

2. Description of the Related Art Since diamond has a high hardness and a wide light transmission region, its application as a coating material for a member or a light transmission window material is under study. Further, diamond, which has a property as a wide band gap semiconductor, has been attracting attention as an electronic device material capable of operating at high temperatures. In order to apply diamond to such applications, it is necessary to process diamond into an arbitrary shape. Especially when considered as an electronic device material,
Microfabrication techniques such as etching are indispensable as techniques for producing element structures and patterns.

Conventionally, as a diamond etching method, a laser irradiation method in an oxygen atmosphere, a reactive ion etching (RIE) method using argon or oxygen as an etching gas, or a physical ion irradiation method is used. Examples include etching.

[0004]

However, since diamond is generally a very hard and chemically stable substance, etching is very difficult. Therefore, the conventional etching method has problems that the etching rate of diamond is low and the shape of the etched surface is not clean.

In order to solve the above-mentioned conventional problems, it is an object of the present invention to provide a method for efficiently and rationally etching diamond.

[0006]

In order to achieve the above object, the method of etching a diamond according to the present invention comprises irradiating a diamond with an accelerated particle mass containing a plurality of molecules or atoms as constituent particles in a reduced pressure atmosphere. Is characterized by.

In the present invention, it is preferable that the mass of the particle agglomerates be unitary. In the present invention,
It is preferable that the state of the particle mass is ionic. Further, in the present invention, the number of constituent molecules or atoms of the particle mass is preferably 2 or more and 10000 or less.
More preferably, the number of constituent molecules or atoms of the particle mass is
It is 100 or more and 5000 or less.

Further, in the above-mentioned present invention, it is preferable that the molecules constituting the particle mass are rare gas molecules. Further, in the above-mentioned present invention, it is preferable that the molecule constituting the particle mass is an argon (Ar) molecule.

Further, in the present invention, it is preferable that the composition of the molecules or atoms forming the particle mass contains at least oxygen element. Further, in the above-mentioned present invention, it is preferable that the molecule constituting the particle mass is a carbon dioxide (CO ₂ ) molecule.

Further, in the present invention, it is preferable that the molecule constituting the particle mass is an oxygen (O ₂ ) molecule.
Further, in the present invention, the energy of the accelerated particle mass is preferably 200 keV or less. A more preferable lower limit is about 5 keV or more when the number of constituent molecules or atoms in the particle mass is 100 or more and 5000 or less.

Further, in the present invention, it is preferable to heat the diamond to a temperature of 650 ° C. or lower when irradiating the accelerated particle mass. A more preferable lower limit is
It is about 400 ° C or higher.

In the present invention, it is preferable that the atmosphere for irradiating the diamond with the particle agglomerates is a reduced pressure atmosphere containing at least a gas composed of molecules having an oxygen element as a constituent element.

Next, the diamond etching apparatus of the present invention introduces a supply gas to generate a particle agglomerate for generating a particle agglomerate having a plurality of molecules or atoms as constituent particles and ionizing the particle agglomerate. An ionization means for
Mass separation means for selecting a predetermined number of molecules or atoms forming the particle mass, accelerating means for accelerating the particle mass, and irradiation means for irradiating a diamond particle surface with a particle mass beam. It is characterized by having.

[0014]

According to the above-described diamond etching method of the present invention, diamond is irradiated efficiently and reasonably by irradiating it with a particle mass in which a plurality of accelerated molecules or atoms are constituent particles. It can be etched.

In general, when a substance is irradiated with particles having a certain amount of energy, the surface layer of the substance is physically etched by the sputtering action. Therefore, by utilizing this phenomenon, the diamond layer surface can be etched by irradiating the diamond with accelerated particles. However, when particles composed of single ions such as normal ions are incident on the diamond for etching, the incident ions are injected into the diamond or the diamond is damaged. Especially in the case of diamond, it is difficult to recover the damage because the graphitization easily occurs due to the damage introduced. In addition, since the incident direction of ions having energy has a strong directional property, it is difficult to form a smooth etching surface without unevenness. As described above, it is not suitable to process a diamond by irradiating a single particle.

On the other hand, when a particle mass composed of a plurality of particles (molecules or atoms) is incident on diamond, even if each particle has the same energy as an individual particle, each individual particle In view of the above, the energy is equivalently low, and the diamond damage can be prevented while the etching effect remains unchanged. In addition, since a multi-body collision effect occurs in the interaction between the incident particle agglomerates and diamond, the sputtering efficiency is actually improved and the etching rate can be increased. At the same time as the incident particle mass collides with the diamond, it decomposes into individual molecules or atoms and changes its momentum (direction / speed) and energy to scatter, so that the sputtering in the lateral direction with respect to the incident direction. The effect becomes remarkable. Therefore, by injecting the accelerated particle lumps into the diamond, it is possible to form a smooth etching surface without unevenness.

Further, if the particle mass incident on the diamond is sorted by mass and only the particle mass having a predetermined mass is incident, the etching can be performed with higher accuracy. Further, when the state of the incident particle agglomerates is ions, acceleration of the particle agglomerates, direction control of the particle agglomerates, mass selection of the particle agglomerates, etc. become easy.

The number of constituent molecules or atoms in the particle mass is
When the number is 2 or more and 10000 or less, it becomes possible to more efficiently generate and etch particle agglomerates. Further, when the molecules forming the particle agglomerates are rare gas molecules, for example, argon (Ar) molecules, it becomes possible to easily form the particle agglomerates suitable for etching.

When the composition of the molecules or atoms forming the particle mass contains at least oxygen element, the etching efficiency is improved not only by physical etching but also by chemical effect.

When the molecules forming the particle agglomerates are carbon dioxide (CO ₂ ) molecules or oxygen (O ₂ ) molecules, it becomes possible to easily form particle agglomerates suitable for etching. The energy of the accelerated particle mass is 200 ke
When it is V or less, the diamond can be etched with almost no damage.

Further, when irradiating the accelerated particle agglomerates, heating the diamond to a temperature of 650 ° C. or lower enables efficient etching. Further, when the atmosphere for irradiating the diamond with the particle agglomerates is a reduced pressure atmosphere containing at least a gas composed of molecules having an oxygen element as a constituent element, it becomes possible to perform etching efficiently.

Next, according to the diamond etching apparatus of the present invention, a supply gas is introduced to generate a particle agglomerate for generating a particle agglomerate having a plurality of molecules or atoms as constituent particles, and the particle agglomerate. Ionization means for ionizing, mass separation means for selecting a predetermined number of molecules or atoms forming the particle mass, accelerating means for accelerating the particle mass, and particle mass beam on the surface of diamond By providing the irradiation means for irradiating
The diamond can be smoothed efficiently and rationally.

[0023]

EXAMPLES In order to facilitate understanding of the diamond etching method of the present invention, preferred examples thereof will be described in detail below.

First, the basic structure of the apparatus used in one embodiment of the present invention will be described with reference to FIG. In FIG. 1, a particle agglomerate is generated from the gas introduced into the particle agglomerate generator 4, the particle agglomerate is ionized in the ionization unit 5, and then the molecules or atoms constituting the particle agglomerate are predetermined in the mass separator 6. The number of particles is selected and then accelerated by the acceleration unit 7, and the irradiation unit 8 irradiates the surface of the diamond 2 with the particle agglomerate beam 1. The surface of the diamond 2 is masked with a mask material 3.

Any method may be used as a method for producing particle agglomerates, but in general, a gas cluster method for producing a particle agglomerate by gas constituent atoms or molecules using a gas raw material is optimum Is. In this embodiment, FIG.
The nozzle 11 is provided on the wall of the vacuum container 9 of the particle lump production section 4 of FIG. 1, and gas is introduced into the gas introduction port 10 of the nozzle 11 from the outside. That is, the gas supplied at a pressure of 2 atm or more is injected at supersonic speed, and the exhaust pump 13 is used to generate 1 × 10
Adiabatic expansion is performed in a container kept in a reduced pressure atmosphere in the range of ^-4 to 1 x 10 ^-6 Torr. As a result, a gas cluster source consisting of a skimmer that shapes the shape of the particle beam obtained by agglomeration was used. The nozzle 11 is made of, for example, quartz glass, and its sectional view is as shown in FIG. Figure 2
In the figure, 21 is a gas supply port, 22 is a constricted portion, and 23 is a gas discharge port (injection port). The opening diameter a of the gas supply port 21 is about 8 mm, the length d is about 20 mm, the opening diameter b of the constricted portion 22 is about 0.1 mm, and the gas discharge port (injection port) 23.
Has an opening diameter c of about 3 mm and a length e of about 30 mm.
The molecules and atoms that make up the particle mass obtained by this method are weakly bound to each other by forces such as van der Waals forces. Generally, the size of the particle agglomerates (the number of constituent particles) can be controlled by the pressure of the source gas supplied or the size of the holes (diameter: about 0.1 mm or less) provided in the nozzle. With such a gas cluster source,
A particle agglomerate beam can be easily generated from a rare gas such as Ar or a molecular gas or compound gas such as CO ₂ or O ₂ . Further, the mixed gas or the like can be used depending on the purpose of use. The particle mass passes through the skimmer 12 shown in FIG. 1 and is sent to the ionization section 5.

The ionization section 5 gives an electric charge to individual particle agglomerates by electron impact or other methods in order to facilitate control of focusing and acceleration of the particle agglomerate beam. One of them is given a monovalent charge. That is, since one of a population of tens to thousands of molecules / atoms is ionized, each particle mass acts as a monovalent ion having a mass of tens to thousands of times. For example, the ionization method can be performed by an electron impact method using thermoelectrons emitted from the ionizer 15. The specific condition of this method is W
An ionization electron voltage of 150 V was applied to a filament made of (tungsten) to draw out thermoelectrons to ionize the particle agglomerates. The ionization unit 5 is the exhaust pump 1
4 was used to maintain a reduced pressure atmosphere in the range of 1 × 10 ⁻⁵ Torr or less.

Next, the mass separation unit 6 uses the mass separation filter 16 or the like to sort the generated particle mass according to its mass. That is, it is intended to select a predetermined number of molecules or atoms constituting a particle agglomerate, and by this operation, a uniform particle agglomerate beam can be obtained. The method of mass separation is not particularly limited, but it is a deceleration electric field method of separating by an electric field, a method of using an aberration of an electric field lens, an E × B (E-Cross-Bee filter, or Wien filter) method using a magnetic field. Can be considered. In particular, in the case of mass separation by the deceleration electric field method, since the mass separation is performed by providing the deceleration electrode after the acceleration electrode, the mass separation section becomes linear and the device configuration becomes simple. Further, when the aberration of the electric field lens is used, mass separation is performed by providing an opening through which the desired ion species can pass after the electric field lens for converging the beam. Becomes easier. In this embodiment, the deceleration electric field method is used, and the deceleration electric field voltage of about 0 to 300 V is applied.

The mass separation unit 6 was also kept under reduced pressure in the range of 1 × 10 ⁻⁵ Torr or less by using the exhaust pump 17.
The particle agglomerate beam that has undergone the above-described steps is subjected to an electric field by using the accelerator 18 in the acceleration unit 7,
It is accelerated to a predetermined acceleration energy (50 keV or less) and sent to the irradiation unit 8. In the irradiation unit 8, the beam is deflected by using the deflector 19 to guide the beam to a predetermined irradiation portion, and then the particle agglomerate beam is irradiated to the diamond 2 under appropriate conditions. If the individual particle clusters are composed of N molecules / atoms, the irradiated particle cluster beam is compared with the case where irradiation is performed by a single atom / molecule.
The energy per molecule / atom is 1 / N, the beam current is N times, and the charge-mass ratio is also 1 / N. Therefore, it can be said that the beam is equivalently low energy and large current. The accelerating voltage at this time is preferably 1 keV or more from the standpoint of ion extraction, transport / lens system efficiency, and the like. Further, the number of atoms or molecules forming the particle mass to be irradiated is preferably at least 100 in order to obtain a more lateral sputtering effect, and 5000 or less in terms of particle mass generation efficiency. Is preferred.

The accelerating unit 7 and the irradiating unit 8 use the exhaust pump 20 to have a pressure of 1 × 10 ⁻⁴ Torr or less, preferably 1 × 10 ^{4.
-Keep in} a depressurized atmosphere within a range of ^-6 Torr or less. It should be noted that each part of the device can be modified into a configuration suitable for each embodiment.

FIG. 3 is a schematic view showing a state of irradiation of a particle agglomerate beam according to an embodiment of the present invention. The particle agglomerates 1 generated through the steps such as particle agglomeration, ionization, mass separation, and acceleration are irradiated onto the diamond layer 2 with a predetermined energy. When the irradiated particle mass 1 collides with the diamond layer 2, it is decomposed into individual molecules or atoms, the momentum (direction / speed) and energy thereof are changed, and the surface layer of diamond is sputtered. As a result, diamond is etched efficiently and with a smooth etched surface. Reference numeral 3 is a mask material for selecting a region to be etched. The material of the mask material 3 is not particularly limited, but a silicon dioxide film or the like is often used.

Example 1 First, microwave plasma CVD was performed on a 2 × 2 × 0.5 mm single crystal diamond substrate.
A single crystal diamond layer was formed using the method. The microwave plasma CVD method forms a diamond by applying microwaves to a source gas to form a plasma. In this embodiment, hydrogen as a source gas is 2 to
10 vol. Carbon monoxide gas diluted to about% was used. The thickness of the formed diamond layer was 2 μm. On the surface of the diamond layer, a silicon dioxide film having a predetermined pattern to be etched (thickness 5 μm)
Placed a mask consisting of.

Then, the single crystal diamond thin film formed on the substrate is subjected to a particle agglomerate beam of a diamond etching apparatus.
After irradiating the inside of the apparatus to a vacuum and irradiating the accelerated particle mass. The irradiated particle agglomerates were supplied with argon (Ar) as a raw material gas at an external pressure of 2 to 3 atmospheres to form particle agglomerates of Ar molecules. It was possible to control the number of constituent molecules of individual particle aggregates obtained under such conditions within the range of 200 to 3000. In this embodiment, the supply pressure of the raw material gas is set to 3 atm, and an Ar particle mass composed of about 1000 to 3000 Ar molecules is generated, and then the particle mass is ionized.
The diamond was irradiated with 1 × 10 ¹⁷ ions / cm ² by accelerating with an accelerating voltage of kV. That is, the energy of the entire particle mass is 20 keV, and 1 × 1 per unit area.
Irradiated with a mass of 0 ¹⁷ Ar particles.
r molecule at an energy of about 7 to 20 eV and about 1 to 3 × 10
^{It is} about ²⁰ irradiations. As a result, the diamond layer deposited on the substrate was etched to a depth of about 2 μm. The etched surface was also very smooth with a surface roughness of 100 Å (10 nm) or less.

Similar results were obtained when the same treatment was performed while changing the irradiation conditions such as the irradiation energy or when other rare gas such as xenon was used.

(Example 2) When diamond was irradiated with Ar particle agglomerates under the same conditions as in Example 1, the diamond was heated. The heating temperature was 600 ° C. as a result,
The smoothness of the etched surface of diamond did not change, the etching rate increased, and more efficient diamond etching was performed.

Similar results were obtained when the same treatment was performed by changing the irradiation conditions such as the irradiation energy or when another rare gas such as xenon was used.

(Embodiment 3) Similar to the above example, 2 × 2 ×
A single crystal diamond formed on a 0.5 mm single crystal diamond substrate was prepared and irradiated with Ar particle agglomerates generated from a gas cluster source. Irradiation A in this embodiment
r particle agglomerates were sorted by mass and only particle agglomerates with a single particle number were irradiated. Irradiation condition is Ar: particle number: 3000
Ionize the particle agglomerates and accelerate with a voltage of 20 kV, 1 ×
The diamond was irradiated with 10 ¹⁷ ions / cm ² . As a result, the etching rate of diamond did not change, the smoothness of the etching surface was better than that of Example 1, and more accurate diamond etching was performed.

Similar results were obtained when the same treatment was performed while changing the irradiation conditions such as the irradiation energy or when another rare gas such as xenon was used.

(Embodiment 4) As in the above example, 2 × 2 ×
A single crystal diamond formed on a 0.5 mm single crystal diamond substrate was prepared and irradiated with Ar particle agglomerates in a reduced pressure atmosphere containing oxygen at a pressure of 5 × 10 ⁻⁵ Torr. Irradiation conditions are as follows: the supply pressure of the source gas is 3 atm, Ar particle agglomerates are generated, and after the particle agglomerates are ionized, 2
The diamond was irradiated with 1 × 10 ¹⁷ ions / cm ² by accelerating with an accelerating voltage of 0 kV. As a result, as compared with the case of Example 1, the smoothness of the etched surface of diamond did not change, the etching rate increased, and more efficient diamond etching was performed.

Similar results were obtained when the same treatment was performed while changing the irradiation conditions such as the irradiation energy or when another rare gas such as xenon was used.

(Embodiment 5) As in the above example, 2 × 2 ×
A single crystal diamond formed on a 0.5 mm single crystal diamond substrate was prepared and irradiated with CO ₂ particle agglomerates generated from a gas cluster source. The irradiation condition is the number of particles:
Ionization of 1000 to 2000 CO ₂ particle agglomerates 2
The diamond was irradiated with 1 × 10 ¹⁷ ions / cm ² by accelerating with a voltage of 0 kV. As a result, the diamond layer deposited on the substrate is etched, and the etched surface also has a surface roughness of 100 Å (10 nm).
The following was very smooth.

Similar results were obtained when the same treatment was performed while changing the irradiation conditions such as the irradiation energy or when another gas such as oxygen was used.
Similar results were obtained when the particles were irradiated, when the diamond was heated, when the irradiated particles were sorted by mass, or when the particles were irradiated in a reduced pressure atmosphere containing oxygen.

In the above embodiment, the case where the diamond layer to be etched is a single crystal diamond film formed by the CVD method has been described as an example.
The diamond is not necessarily limited, and may be a diamond including a polycrystalline diamond film formed by a CVD method or a single crystal diamond formed by high pressure synthesis.

[0043]

As described above, according to the present invention, by irradiating diamond with a particle mass composed of a plurality of accelerated particles or atoms as constituent particles in a reduced pressure atmosphere, the diamond is not damaged. It can be easily and efficiently etched.

Further, if the particle mass incident on the diamond is sorted by mass and only the particle mass having a predetermined mass is incident, it becomes possible to perform etching with higher accuracy. Furthermore, by making the state of the incident particle agglomerates into ions, it becomes possible to facilitate acceleration of the particle agglomerates, control of the direction of the particle agglomerate flow, mass selection of the particle agglomerates, and the like.

Further, by setting the number of constituent molecules or atoms of the particle agglomerates to be 2 or more and 10000 or less, it becomes possible to more efficiently generate and etch the particle agglomerates. Further, by using a rare gas molecule such as an argon (Ar) molecule as a molecule forming the particle mass, it becomes possible to easily form a particle mass suitable for etching.

Further, by making the composition of the molecules or atoms forming the particle mass at least include the oxygen element, the etching efficiency is improved not only by the physical etching but also by the chemical effect.

Further, by using carbon dioxide (CO ₂ ) molecules and oxygen (O ₂ ) molecules as the molecules constituting the particle mass,
It becomes possible to easily form a particle mass suitable for processing. The energy of the accelerated particle mass is 200 ke
By setting it to V or less, the diamond can be etched with almost no damage.

By heating the diamond to a temperature of 650 ° C. or lower when irradiating the accelerated particle mass, it becomes possible to efficiently etch the diamond. Furthermore, by setting the atmosphere for irradiating the diamond with the particle agglomerates to a reduced pressure atmosphere containing a gas composed of molecules having at least an oxygen element as a constituent element, it becomes possible to perform etching efficiently.

Next, according to the diamond etching apparatus of the present invention, a particle agglomerating means for introducing a supply gas to generate a particle agglomerate having a plurality of molecules or atoms as constituent particles, and the particle agglomerate. Ionization means for ionizing, mass separation means for selecting a predetermined number of molecules or atoms forming the particle mass, accelerating means for accelerating the particle mass, and particle mass beam on the surface of diamond By providing the irradiation means for irradiating
The diamond can be smoothed efficiently and rationally.

[Brief description of drawings]

FIG. 1 is a diagram showing steps of a processing apparatus for etching a diamond surface according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a nozzle used in the device.

FIG. 3 is a schematic diagram showing a state of irradiation of a particle agglomerate beam according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Particle mass 2 Diamond layer 3 Mask material 4 Particle mass generation part 5 Ionization part 6 Mass separation part 7 Acceleration part 8 Irradiation part 9 Vacuum container 10 Gas introduction port 11 Nozzle 12 Skimmer 13, 14, 17, 20 Exhaust pump 15 Ionizer 16 Mass Separation Filter 18 Accelerator 19 Deflector 21 Gas Supply Port 22 Constriction 23 Gas Ejection Port

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Makoto Kitahata 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Takashi Hirao, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (13)

[Claims] 1. A method for etching diamond, which comprises irradiating a diamond particle in a reduced pressure atmosphere with a particle mass of accelerated particles or constituent particles. 2. The diamond etching method according to claim 1, wherein the mass of the particle agglomerates is unity. 3. The state of the particle aggregate is an ion.
The method for etching a diamond according to. 4. The number of constituent molecules or atoms of a particle mass is 2
The method for etching diamond according to claim 1, wherein the number is 1 or more and 10000 or less. 5. The method for etching diamond according to claim 1, wherein the molecules forming the particle mass are rare gas molecules. 6. The molecules constituting the particle mass are argon (A
The method for etching diamond according to claim 1, wherein r is a molecule. 7. The diamond etching method according to claim 1, wherein the composition of molecules or atoms forming the particle mass contains at least oxygen element. 8. The diamond etching method according to claim 1, wherein the molecules forming the particle aggregate are carbon dioxide (CO ₂ ) molecules. 9. The molecule constituting the particle mass is oxygen (O ₂ )
The method for etching diamond according to claim 1, wherein the etching is a molecule. 10. The energy of the accelerated particle mass is 2
The diamond etching method according to claim 1, wherein the etching voltage is 00 keV or less. 11. The diamond etching method according to claim 1, wherein the diamond is heated to a temperature of 650 ° C. or lower when the accelerated particle mass is irradiated. 12. The diamond etching method according to claim 1, wherein the atmosphere for irradiating the diamond with the particle agglomerates is a reduced pressure atmosphere containing a gas composed of molecules having at least an oxygen element as a constituent element. 13. A device for etching a diamond surface, which comprises introducing a supply gas to generate a particle agglomerate for generating a particle agglomerate having a plurality of molecules or atoms as constituent particles, and ionizing the particle agglomerate. Ionization means for, a mass separation means for selecting a predetermined number of molecules or atoms forming the particle mass, an acceleration means for accelerating the particle mass, and a particle mass beam on the surface of the diamond. An etching device for diamond, comprising: an irradiation unit for irradiation.