JPH05283370A - Fine processing device - Google Patents

Abstract

PURPOSE:To materialize the processing of high aspect structure with an optional length and where both the shape and the finishing face are highly accurate, regardless of the quality of material to be processed. CONSTITUTION:The mixed gas of the reaction gas and the inert gas supplied from a reaction gas supply means 12 and an inert gas supply means 13 is introduced into a vacuum vessel 11. A plasma generation source 16 is provided on one side of this vacuum vessel 1, and the mixed gas is made plasma by this plasma generation source 16. This plasma P is throttled into a beam shape at and around the surface of a material 22 to be processed, by the magnetic field generated by electromagnetic coils 25, 26, and 27, and it is applied to material 22 to be processed. Hereby, reactive seeds such as ions, radicals, or the likes high in reactive activity in excited condition within a plasma beam Po chemically react on the surface of the material 22 to be processed, receiving the assistance of the application energy of the plasma beam Po, whereby the surface of the material 22 to be processed is etched (or deposited) on an atom level.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fine processing apparatus having a function of irradiating a material to be processed with a plasma beam to perform fine processing.

[0002]

2. Description of the Related Art Conventionally, an electric discharge machining apparatus has been known as a typical micromachining apparatus for forming fine trenches and fine holes. This electric discharge machine, as shown in FIG.
The material 2 to be processed is held by the holder electrode 3 in the oil 1a in the oil storage tank 1 and installed. Then, above the material 2 to be processed, a processing electrode 4 made of a tungsten wire or the like is provided.
Is supported by the feed mechanism 5 so as to be vertically movable and rotatable.

At the time of fine processing, the feed mechanism 5 operates to rotate the processing electrode 4 and feed it in the direction (downward) of the material 2 to be processed, and at the same time, the holder electrode 3 (material 2 to be processed) and the processing electrode 4 are moved. A high DC voltage V is applied through the discharge circuit 6 in the meantime. As a result, an electric discharge is generated between the material 2 to be processed and the processing electrode 4 to form an electric discharge mark (crater) on the material 2 to be processed, and the accumulation of the electric discharge mark forms, for example, a processing hole as shown in FIG. 7 is formed.

[0004]

However, in the above-mentioned electric discharge machining apparatus, since the fine machining is realized as the accumulation of electric discharge marks, there is a drawback that the finished surface roughness is generally rough.

In this case, the discharge energy E = C · V ² /
2 (C: capacitor capacity, V: voltage applied between electrodes) can be made small to a small extent, but in order to make discharge energy E small, it is necessary to reduce stray capacitance in the device as much as possible. However, there is a drawback that the device cost becomes high. Moreover, since the material 2 to be processed is limited to the conductive material in order to generate the electric discharge, there is a drawback that the processing target range is narrow.

Further, as shown in FIG. 8, as the depth of the processed hole 7 increases (the aspect ratio increases),
Since the machining electrode 4 advances through the material 2 to be machined, not only the discharge at the tip of the machining electrode 4 but also the peripheral side surface of FIG.
The discharge proceeds as indicated by the arrow. For this reason, there is a disadvantage that a hole diameter L1 on the upper surface of the material 2 to be processed and a hole diameter L2 on the lower side are different from each other and a uniform hole diameter cannot be obtained.

In addition to such an electric discharge machining apparatus, LIGA (Li
thograpie Galvanoformung Abformung) process. In this LIGA process, PMMA (polymethylmethacrylate) resist is applied thickly on a substrate, photolithography is performed by X-rays, electron beams, etc., and metal or the like is cast into the mold of this resist to achieve high-quality. It forms an aspect structure.

However, in the LIGA process, it is necessary to use an expensive SOR (Synchrotron Orbital Radiation), and there is a disadvantage that the cost of the apparatus is significantly increased.

The present invention has been made in consideration of such conventional circumstances, and therefore, its object is to achieve high precision in both shape accuracy and finished surface regardless of the material of the material to be processed, and at any depth. Another object of the present invention is to provide a fine processing apparatus capable of realizing high aspect structure processing at low cost.

[0010]

In order to achieve the above object, a fine processing apparatus of the present invention comprises a reaction gas supply means for supplying a reaction gas, a plasma generation source for converting the supplied reaction gas into a plasma, A plasma converging means for converging the generated plasma in a beam shape near the surface of the material to be processed by a magnetic field or an electric field and irradiating the material to be processed is provided (claim 1).

In this case, the reaction gas supply means may supply the reaction gas near the plasma beam irradiation portion on the surface of the material to be processed (claim 2).

The plasma converging means may have a function of changing the irradiation position of the plasma beam on the material to be processed by changing the magnetic field or the electric field (claim 3).

[0013]

According to the above structure, the reaction gas supplied by the reaction gas supply means is turned into plasma by the plasma generation source, and the magnetic field or electric field generated by the plasma converging means is applied to the generated plasma to generate the plasma. The material to be processed is irradiated with a beam in the vicinity of the surface of the material to be processed. As a result, the reactive species such as chemically active ions and radicals in the excited state in the plasma beam chemically react with the surface of the material to be processed with the assistance of the irradiation energy of the plasma beam, and Etch (or deposit) the surface at the atomic level.
Therefore, fine processing is possible regardless of the material of the material to be processed, and the shape accuracy and the finished surface are highly accurate as compared with the conventional electric discharge machining.

Moreover, since the plasma beam can be made into a parallel beam which is sufficiently narrowed down by the magnetic field or electric field generated by the plasma converging means, the irradiation time can be changed to process the high aspect structure of any depth. Can be realized at low cost. Further, since the temperature of the plasma beam irradiation portion of the material to be processed does not rise so much, damage to the material to be processed due to heat can be prevented.

On the other hand, when the life of the reactive species in the plasma is long, the reactive species may diffuse into a portion other than the irradiation portion and etch (or deposit) the portion. Even in this case, if the reaction gas is supplied to the vicinity of the plasma beam irradiation portion on the surface of the material to be processed as described in claim 2, unnecessary diffusion of the reactive species is avoided, and the non-irradiation portion is etched (or deposited). It won't end up.

Further, by changing the magnetic field or the electric field generated by the plasma converging means as in claim 3, the irradiation position of the plasma beam on the material to be processed is changed according to the processing shape, so that the material to be processed is changed. The processed shape can be a desired shape without changing the position.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. Vacuum chamber 11 for containing plasma P
A mixed gas of a reaction gas and an inert gas supplied from the reaction gas supply means 12 and the inert gas supply means 13 through the intake valves 14 and 15, respectively, is introduced therein.

On the left side portion of the vacuum chamber 11 in FIG. 1, an ECR (electron cyclotron resonance) type plasma generation source 16 is provided. The ECR type plasma generation source 16 is provided with an ionization chamber 17 communicating with the vacuum chamber 11 and an electromagnetic coil 18 for applying a magnetic field in the ionization chamber 17, and guides microwaves generated by a magnetron (not shown). It is introduced into the ionization chamber 17 through a pipe 19 and the ionization chamber 17
The mixed gas is ionized by microwave discharge excitation in the inside to be turned into plasma. In this case, the frequency of the microwave introduced into the ionization chamber 17 matches the cyclotron resonance frequency of the electrons determined by the magnetic field generated by the electromagnetic coil 18. As a result, the electrons of the gas molecule are resonantly accelerated, and the gas molecule is excited and ionized to be turned into plasma. In this way, the plasma generated in the discharge chamber 17 is discharged into the vacuum chamber 11 through the opening 17a of the ionization chamber 17.

On the other hand, in the right side portion of the vacuum chamber 11 in FIG.
An irradiation chamber 21 is provided by the bellows 20, and a material 22 to be processed is held in the irradiation chamber 21 by an insulating holder 23. This work material 22 includes a bias power source 2
4 makes it possible to apply an appropriate bias voltage. When the material 22 to be processed is an insulator (dielectric), the bias power supply 24 is a high frequency power supply.

Further, in the portion of the vacuum chamber 11 near the material 22 to be processed, two types of electromagnetic coils 2 serving as plasma focusing means are provided.
5, 26 are provided, and the magnetic field generated by both electromagnetic coils 25, 26 converges the plasma P into a beam shape in the vicinity of the surface of the material 22 to be processed and irradiates the material 22 to be processed. Further, in order to narrow the plasma beam Po to a minute diameter on the surface of the material 22 to be processed, a minute electromagnetic coil 27 as a plasma converging means is also provided on the back side of the insulating holder 23 behind the material 22 to be processed. .. In this case, the fine adjustment of the diameter of the plasma beam Po is performed by expanding and contracting the bellows 20 to move the material 22 to be processed and the electromagnetic coil 27 back and forth. On the other hand, the gas used for the reaction is exhausted through the exhaust valve 28.

The microfabrication apparatus according to this embodiment has a vacuum chamber 1
The plasma P generated in 1 is dispersed to monitor the reaction, or the magnetic field distribution is changed by adjusting the amount of current passed to each electromagnetic coil 25, 26, 27 and the applied voltage to change the processing width and It is also possible to adjust the depth and increase the processing speed.

In this case, the reaction gas supplied into the vacuum chamber 11 is, for example, HBr, depending on the material of the material 22 to be processed.
By using an etching gas such as O, F, Br, CF ₄ , Cl ₂ or the like, the material 16 to be processed can be subjected to trench processing. On the other hand, the deposition gas (eg SiH ₄ , WF
₄ / H ₂ mixed gas, etc.), it is possible to grow fine projections on the plasma beam irradiation portion by the deposition action, thereby drawing in an arbitrary pattern on the surface of the material 22 to be processed, or It is also possible to use the grown fine protrusions as a component of a micromachine.

On the other hand, as the inert gas mixed with the above reaction gas, for example, argon may be used, and the plasma P can be stably maintained due to the presence of this inert gas.

Next, the trench processing performed by using the fine processing apparatus having the above structure will be described. For example, when a silicon semiconductor is used as the material 22 to be processed, a halogen-based etching gas (HBr) is used as the reaction gas. When a mixed gas of this reaction gas (HBr) and an inert gas (argon or the like) is supplied into the vacuum chamber 11 and ionized by the ECR type plasma generation source 16 to generate plasma, this plasma P is generated in the vacuum chamber. Work material 22 in 11
The magnetic field generated by each of the electromagnetic coils 25, 26 near the surface of the beam is converged into a beam. The plasma beam Po is further focused on the surface of the material 22 to be processed by a magnetic field generated by a minute electromagnetic coil 27 behind the material 22 to be processed, and is irradiated onto the surface of the material 22 to be processed.

As a result, reactive species such as chemically active ions and radicals in the excited state in the plasma beam Po adhere to the plasma beam irradiation part on the surface of the material 22 to be processed, and this reacts with the plasma beam Po. By chemically reacting with the surface of the material 22 to be processed with the assistance of irradiation energy, the surface of the material 22 to be processed is etched at the atomic level to form the fine holes 29. At this time, if an appropriate bias voltage is applied to the material 22 to be processed by the bias power source 24, the plasma beam Po having a small diameter is generated.
2 is effectively irradiated.

The main reaction on the surface of the material to be processed (Si) 22 when HBr is used as the reaction gas is as follows.

Si + HBr → SiHBrx + H This main reaction proceeds in the minute reaction region 30, the surface of the material to be processed (Si) 22 is etched, and the generated main reaction product (SiHBrx) is the material to be processed (SHBrx).
i) Adhere and deposit on the etching sidewall of 22 to form a protective film 31 against etching.

While the irradiation of the plasma beam Po is continued,
The above-described etching and deposition of the protective film 31 on the etching side wall are continued, and the fine holes 29 having an arbitrary depth can be formed with a uniform inner diameter in the depth direction.

At this time, while the positional relationship between the plasma beam Po and the material 22 to be processed is kept constant, the distribution of the magnetic fields generated by the electromagnetic coils 25, 26 and 27 is changed to change the irradiation position of the plasma beam Po. If the shape is changed according to the processed shape, the trench can be formed in an arbitrary pattern without changing the position of the material 22 to be processed.

Workpiece material 22 finely processed in this way
Of course, it is possible to use it as it is, and to form a plurality of high aspect structures by using this as a mold and pouring a metal or the like into the mold (electroforming or the like).

In the fine processing using the plasma beam Po, reactive species such as chemically active ions and radicals in an excited state in the plasma beam Po are covered with the assistance of irradiation energy of the plasma beam Po. Processing material 2
Since the surface of the material to be processed 22 is etched at the atomic level by chemically reacting with the surface 2, the material of the material to be processed 22 may be semiconductor, metal (conductor) or insulator (dielectric). It is capable of fine machining and has higher precision in shape and finished surface than conventional electrical discharge machining.

Moreover, since the plasma beam Po can be made into a parallel beam which is sufficiently narrowed down by the magnetic fields generated by the electromagnetic coils 25, 26, 27, the irradiation time can be changed so that the plasma beam Po has a high depth of arbitrary depth. The processing of the aspect structure can be realized at low cost. Further, since the temperature of the plasma beam irradiation portion of the work material 22 does not rise so much, it is possible to prevent the work material 22 from being damaged by heat.

In the above-described first embodiment, the ECR type plasma generation source is adopted as the plasma generation source 16,
An electron gun 32 may be employed as in the second embodiment of the present invention shown in FIG. The electron gun 32 includes a hot cathode 33 and an anode 34. Electrons emitted from the hot cathode 33 are accelerated between the hot cathode 33 and the anode 34 to, for example, about 100 eV to generate an electron beam in the vacuum chamber 11. Will be released.
The electron beam collides with the molecules of the mixed gas introduced into the vacuum chamber 11 and excites / ionizes the molecules to generate plasma P. This plasma P is generated by each electromagnetic coil 2
The magnetic fields generated by 5, 26 and 27 narrow the light beam into a beam near the surface of the material 22 to be processed. The material 22 to be processed is irradiated with the plasma beam Po, and the etching and the deposition of the protective film 31 on the etching sidewall are performed. The same parts as those in the first embodiment described above are designated by the same reference numerals and the description thereof will be omitted.

Further, in both the first and second embodiments, the irradiation chamber 21 in which the material 22 to be processed is set is provided at a position facing the plasma generation source 16 (electron gun 32). As in the third embodiment of the present invention, the irradiation chamber 21 may be provided at a position orthogonal to the magnetic lines of force generated by the electromagnetic coils 18 and 25, and the exhaust valve 28 may be provided at a position facing the plasma generation source 16. .. In this case, the plasma P in the vacuum chamber 11 is confined by the mirror type magnetic field generated by the electromagnetic coils 18 and 25.

Also in the third embodiment, an electromagnetic coil 26 as a plasma converging means is provided near the irradiation chamber 21 (near the boundary of the plasma P), and is installed behind the electromagnetic coil 26 and the material 22 to be processed. The magnetic field generated by the minute electromagnetic coil 27 causes the plasma P to be focused into a beam near the surface of the material 22 to be processed. The material 22 to be processed is irradiated with the plasma beam Po, and etching and deposition of the protective film 31 on the etching side wall are performed as in the first and second embodiments. The same parts as those in the first embodiment described above are designated by the same reference numerals and the description thereof will be omitted.

By the way, when the life of the reactive species in the plasma P is long, there is a possibility that the reactive species may diffuse into a portion other than the irradiation portion and etch (or deposit) the portion. In this case, it may be configured as in the fourth embodiment of the present invention shown in FIGS.

In the fourth embodiment, the reaction gas supply means 1
The reaction gas supplied from No. 2 is introduced into the vicinity of the irradiation portion of the plasma beam Po1 through the nozzle 35. Therefore, the plasma P1 in the vacuum chamber 11 is mainly the plasma of the inert gas, and the plasma conversion of the reaction gas (the generation of the reactive species that contributes to etching or deposition) is performed by the plasma beam Po1 in the irradiation chamber 21. Area 3 to irradiate
Only 6 will proceed locally. Therefore, unnecessary diffusion of the reactive species is avoided, and the non-irradiated portion (the fine holes 29
(Parts other than) are not etched.
The same parts as those in the first embodiment described above are designated by the same reference numerals and the description thereof will be omitted.

In each of the first to fourth embodiments described above, the electromagnetic coil 27 is provided as the plasma focusing means behind the material 22 to be processed, but this may be replaced with a permanent magnet.

In addition, the plasma converging means is not limited to the one for generating a magnetic field, but may be an electric field for converging the plasma, etc. The present invention can be variously modified without departing from the scope of the invention. Is.

[0040]

As is apparent from the above description, the present invention converts the reaction gas supplied by the reaction gas supply means into plasma by the plasma generation source, and the generated plasma is subjected to the magnetic field or electric field generated by the plasma converging means. Is applied, the plasma is converged into a beam in the vicinity of the surface of the material to be processed and irradiated on the material to be processed, and the surface of the material to be processed is etched (or deposited) at the atomic level. Fine processing is possible regardless of the material used, and shape accuracy, compared to conventional electrical discharge machining,
The finished surface is highly accurate.

Moreover, since the plasma beam can be made into a parallel beam which is sufficiently narrowed down by the magnetic field or electric field generated by the plasma converging means, the irradiation time can be changed to process the high aspect structure of any depth. Can be realized at low cost.

Further, since the reaction gas is supplied to the vicinity of the plasma beam irradiation portion on the surface of the material to be processed, unnecessary diffusion of the reactive species contributing to etching (or deposition) can be avoided and the non-irradiation portion can be prevented. It will not be etched (or deposited).

Further, by changing the magnetic field or electric field generated by the plasma converging means, the irradiation position of the plasma beam on the material to be processed is changed in accordance with the processing shape, so that the position of the material to be processed is changed. Even if it does not exist, the processed shape can be made into a desired shape.

[Brief description of drawings]

FIG. 1 is a sectional view of the entire microfabrication device showing a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a plasma beam irradiation portion.

FIG. 3 is a sectional view of the entire microfabrication device showing a second embodiment of the present invention.

FIG. 4 is a sectional view of the entire microfabrication apparatus showing a third embodiment of the present invention.

FIG. 5 is a sectional view of the entire microfabrication apparatus showing a fourth embodiment of the present invention.

FIG. 6 is an enlarged sectional view of a plasma beam irradiation portion.

FIG. 7 is a system configuration diagram showing an outline of a conventional electric discharge machine.

FIG. 8 is an enlarged sectional view of a hole processed by conventional electric discharge machining.

[Explanation of symbols]

Reference numeral 11 is a vacuum tank, 12 is a reaction gas supply means, 13 is an inert gas supply means, 16 is a plasma generation source, 18 is an electromagnetic coil, 21 is an irradiation chamber, 22 is a work material, 23 is an insulating holder, and 24 is a bias. A power source, 25 to 27 are electromagnetic coils (plasma focusing means), 31 is a protective film, 32 is an electron gun (plasma generation source), and 35 is a nozzle.

Claims (3)

[Claims] 1. A reaction gas supply means for supplying a reaction gas, a plasma generation source for converting the supplied reaction gas into a plasma, and the generated plasma in the form of a beam near a surface of a material to be processed by a magnetic field or an electric field. And a plasma focusing means for irradiating the material to be processed. 2. The microfabrication apparatus according to claim 1, wherein the reaction gas supply means supplies the reaction gas to the vicinity of the plasma beam irradiation portion on the surface of the material to be processed. 3. The fine structure according to claim 1, wherein the plasma converging means has a function of changing an irradiation position of the plasma beam onto the material to be processed by changing a magnetic field or an electric field. Processing equipment.