JPH0557525A - Minute trench working machine and minute trench working method - Google Patents

Abstract

PURPOSE:To embody a high aspect structure having optical depth at low cost. CONSTITUTION:High frequency electric power 31 is applied to workpieces 10 and a working electrode 21 with a cathode coupling, and a plasma region 60 is formed on the tip of the working electrode 21. The introduction of a reaction gas 50 into the plasma region 60 causes the activation of the reaction gas and the adsorption of an active gas to a workpiece 10 surface opposite to the tip of the working electrode 21, and the reaction of the active gas to the workpiece 10 results in the etching of the workpiece 10 surface. The working electrode 21 is delivered in the workpiece 10 direction with a feed mechanism according to etching to trench 11 the workpiece 10. The reaction product of the workpiece and the reaction gas produced by the etching reaction is stuck and deposited on a side wall of a trench 11 to become a protective film 12 to etching, embodying the high aspect structure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microfabrication technique, and for example, a microtrench suitable for forming a microtrench having a high aspect ratio necessary for a shaft hole of a micromotor or a pressure introduction hole of a pressure sensor. The present invention relates to a processing machine and a fine trench processing method.

[0002]

2. Description of the Related Art Conventionally, an electric discharge machining technique has been known as one of precision machining techniques for forming fine trenches and fine holes. FIG. 6A shows a schematic configuration diagram of a fine hole electric discharge machine using this electric discharge machining technique.

In FIG. 6 (a), reference numeral 110 denotes a material to be processed (work) to which fine hole processing is applied, and the holder electrode 1
It is held at 30 and installed in oil 100. Also,
A machining electrode 121 is made of a material such as a tungsten wire which has a high rigidity and does not break due to internal defects even when formed into a small diameter. The machining electrode 121 is fed by the feed mechanism 120 toward the material 110 to be processed while rotating.

Here, the fine hole machining by the electric discharge machining technique is realized as an accumulation of single electric discharge marks, that is, craters. In FIG. 6A, the RC circuit is replaced by the discharge circuit 13
The single discharge energy E (J) is represented by the following equation.

[0005]

[Equation 1] E = (C · V ² ) / 2, where C is the capacitance of the capacitor, V is the voltage applied between the poles. That is, the material 1 to be processed is generated by this single discharge energy E.
By sending out the machining electrode 121 while the electric discharge machining of 10 is performed, it is possible to perform fine hole machining on the material 110 to be machined.

However, in the fine hole machining using this electric discharge machining, the machined hole is realized as an accumulation of a single electric discharge mark, that is, a crater as described above, so that the finished surface has a rough surface. In order to reduce the finished surface roughness, it is necessary to consider as much as possible the stray capacitance in the device so that the discharge energy E expressed by the above-mentioned formula 1 is made minute.

Further, since electric discharge machining is used as a processing method, there is a problem that the materials that can be processed are limited to conductive materials. Furthermore, as the depth of the processing hole 111 increases (the aspect ratio is large), the processing electrode 121 advances in the material 110 to be processed, and not only the discharge at the tip of the processing electrode 121 but also the discharge on the side of the body progresses. However, as shown in FIG. 6B, there arises a difference between the hole diameter L ′ on the upper surface of the material to be processed 110 and the hole diameter L below, which makes it difficult to obtain a uniform hole diameter. is there.

[0008] In addition, as a typical one for forming a high aspect structure, LIGA (Lithograpie Galv
anoformung Abformung) process.
In this process, a PMMA resist is applied thickly on a substrate, photolithography is performed by X-ray or the like, and a metal or the like is cast into a mold of this resist to form a high aspect structure.

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

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has high accuracy in both shape accuracy and finished surface regardless of the material of the material to be processed.
The purpose is to realize a high aspect structure with an arbitrary depth at low cost.

[0011]

In order to achieve the above object, in a fine trench processing machine and a fine trench processing method according to the present invention, a reaction gas is locally decomposed and dissociated between a tip portion and a material to be processed. An ultrafine wire-shaped member capable of forming a region to be an active species (for example, a plasma region or a photo-assisted reaction region) is arranged facing the material to be processed. A technical means is adopted in which the material to be processed is sent in and removed locally while keeping a constant distance from the etching bottom surface, and reaction products are sequentially deposited on the etching sidewall of the material to be processed.

[0012]

The reaction gas is decomposed and dissociated in the local region between the etching bottom surface of the material to be processed and the tip of the ultrafine wire member, and becomes an active species to etch the material to be processed at the atomic level. Therefore, regardless of the material of the material to be processed, the finished surface roughness can be made much smaller than that of the conventional electric discharge machining.

Here, since the ultrafine wire member is fed in the direction of the material to be processed so that the distance between the etching bottom surface and the tip of the ultrafine wire member is kept constant, the high aspect structure of arbitrary depth is formed. Can be realized.

Further, the reaction gas is decomposed and dissociated only in the local region between the etching bottom surface of the material to be processed and the tip portion of the ultrafine wire member, so that the material to be processed is not damaged outside this region. In other words, the etching sidewall of the material to be processed is unlikely to be etched in all regions except the vicinity of the etching bottom surface. Further, the reaction products formed in the reaction region are sequentially deposited on the etching sidewall and act as a protective film, so that etching by the active species is further suppressed on the etching sidewall, and the etching sidewall can have a uniform shape in the depth direction. it can.

As described above, according to the present invention, regardless of the material of the material to be processed, it is possible to realize a high aspect structure of arbitrary depth with high accuracy in shape accuracy and finished surface at low cost. ..

[0016]

The present invention will be described below with reference to the embodiments shown in the drawings. FIG. 1 shows a system configuration diagram of a fine trench processing machine to which the first embodiment of the present invention is applied. In FIG. 1, 10
Is a material to be processed, and is held by the holder electrode 30 in the vacuum chamber 40. The holder electrode 30 constitutes a cathode electrode,
It has a so-called cathode coupling structure to which the high frequency power 31 is applied.

Further, in the vacuum chamber 40, a processing electrode (extra fine wire member) 21 serving as an anode electrode is arranged with respect to a holder electrode 30 constituting a cathode electrode. The machining electrode 21 is made of a material such as a tungsten wire which has a high rigidity and does not break due to internal defects even when formed into a small diameter, and is fed by the feeding mechanism 20 toward the material 10 to be processed. The processing electrode 2
The diameter of 1 can be set according to the diameter of the trench in the material 10 to be processed, and by exchanging it, it is possible to perform trench processing of different diameters.

In addition, the reaction gas 50 is introduced into the vacuum chamber 40 through the intake port 41.
0 becomes reactive species such as radicals and ions due to the high frequency power 31 applied between both electrodes, and the reactive species etch the material 10 to be processed by chemical reaction and local collision with the material 10 to be processed. Here, the feeding speed of the working electrode 21 by the feeding mechanism 20 is set in advance in accordance with the working conditions, and the distance between the tip of the working electrode 21 and the surface of the material 10 to be worked relative to the tip is always controlled to be constant. Is advanced.

The gas used for the reaction is exhaust port 42.
More discharged. The plasma generated in the vacuum chamber 40 can be spectrally dispersed to monitor the reaction, thereby making it possible to improve the precision and speed of processing, or detect the end.

Next, with reference to FIG. 2, the trench processing which proceeds by etching will be described. In FIG.
When a semiconductor (silicon) is used as the material 10 to be processed, a halogen-based gas can be used as the reaction gas 50 introduced into the vacuum chamber 40.

When the machining electrode 21 is opposed to the material 10 to be processed by the feed mechanism 20 and the power source 31 is connected to the machining electrode 21 and the material 10 to be processed, a local plasma region 60 is formed during this period. In the plasma region 60, the reactive gas 50 is decomposed and dissociated into active species such as radicals and ions, and the active species are adsorbed on the surface of the material to be processed exposed to the plasma region 60 and react with the material 10 to be processed. By this, local etching removal proceeds. The main reaction on the surface of the material to be processed (Si) 10 when HBr is used as the main reaction gas is as follows.

[0022]

Embedded image Si + HBr → SiBr _X + H Then, the main reaction product (SiBr) generated by etching the surface of the material (Si) 10 to be processed by this reaction
_X ) adheres to and deposits on the etching side wall of the material to be processed,
A protective film 12 for etching is formed.

By feeding the processing electrode 21 into the material 10 to be processed by the feeding mechanism 20 so as to keep a constant distance from the etching bottom surface of the material 10 to be processed, the above-mentioned etching and the deposition of the protective film 12 on the etching sidewall are continued. However, it is possible to form the trench 11 having an arbitrary depth with a uniform inner diameter in the depth direction.

At this time, the processing electrode 21 is connected to the material 10 to be processed.
A single trench is formed in the case of being fed perpendicularly to, but the trench can be formed in an arbitrary pattern by scanning the processing electrode in the in-plane direction of the material 10 to be processed.

The processed material 10 thus processed is used as it is, and a plurality of high aspect structures are formed by a method of using this as a mold and casting metal or the like into this mold (electroforming, etc.). It is also possible to do so.

The material to be processed is not limited to semiconductors, and various metals, dielectrics and insulators can be applied. In that case, the reaction gas that contributes to the etching reaction as active species such as ions and radicals may be changed depending on the material of the material to be processed.
O, F, Br type gases, etc. can be set appropriately.

Next, FIG. 3 is a schematic structural diagram of a fine trench processing machine according to a second embodiment of the present invention. In this embodiment, an optical fiber 71 is used as an ultrafine wire member instead of the processed electrode 21 in the first embodiment.
By irradiating the material to be processed with light from the tip of, the reaction gas 50 is decomposed and dissociated in the local region (light assisted reaction region) 75 irradiated with light to form active species. That is, the active species are formed by using plasma in the first embodiment, whereas the active species are formed by light energy in the present embodiment. In FIG. 3, 70
Is a light source such as a laser. In this embodiment as well, as in the first embodiment, active species are formed only at the tip of the optical fiber 71, so that etching and the protective film 1 on the etching sidewall are performed.
2 can be deposited.

Further, the first embodiment and the second embodiment are appropriately combined, and for example, a laser beam or the like is irradiated while the reaction gas is dissociated by plasma to promote the reaction between the reaction gas and the material to be processed. However, it is also possible to form a deep trench.

FIG. 4 is a structural view of the essential portions of the third embodiment of the present invention. This embodiment prevents unnecessary plasma discharge between the side wall of the processing electrode 21 and the etching side wall of the workpiece 10 by coating the insulating material 22 on the side wall of the processing electrode 21 in the first embodiment. , Selective machining electrode 2
The reaction gas is decomposed and dissociated only at the tip of 1.

FIG. 5 is a structural view of the essential parts of a fine trench processing machine according to the fourth embodiment of the present invention. This embodiment is the same as the third embodiment.
A tubular cavity 23 is provided inside the processing electrode 21 in the embodiment, and the reaction gas 50 is introduced from this cavity 23. In the above-mentioned first to third embodiments, the reaction gas 50 diffuses in the vacuum chamber 40, so that the trench 1 of the material 10 to be processed is
However, it becomes difficult for gas to enter as the trench depth increases. This becomes remarkable especially when the clearance between the machining electrode 21 or the optical fiber 71, which is an ultrafine wire member, and the trench 11 is small. For this reason, in the fourth embodiment, the reaction gas 50 is discharged from the tip of the processing electrode 21 so that the reaction gas 50 surely reaches the bottom of the trench, that is, the dissociation region of the tip of the ultrafine wire member. That is, fresh gas is always supplied to the plasma region 60, and the gas after the reaction is processed electrode 21.
The reaction gas flows upward along the space between the trench 11 and the trench 11, and the reaction gas can be prevented from staying in the trench.

The fourth embodiment is of course applicable to the second embodiment using the above-mentioned optical assist. As described above with reference to various embodiments, the reaction gas 50 is used for etching the bottom surface of the material 10 to be processed and the ultrafine wire member (processing electrode 2).
1, the optical fiber 71) is decomposed and dissociated only in a local region (plasma region 60, photo-assisted reaction region 75) between the tip portion of the optical fiber 71), and the work material 10 is not damaged outside this region. That is, the material to be processed 10
Etching will proceed in the immediate vicinity of the etching bottom surface. This is also related to the fact that the reaction product formed by the etching reaction in the reaction region adheres and deposits on the side wall of the trench 11 after being etched, and acts as the protective film 12 (side wall protective effect).

From the above, the ultrafine wire member (machining electrode 2
1. By feeding the optical fiber 71) toward the material 10 to be processed by the feed mechanism 20, the material 10 can be formed into a trench to an arbitrary depth, and the side wall of the trench 11 is formed in the reaction region. The shape can be made uniform in the depth direction without being affected by the active species. In addition, since the trench formation also uses an etching reaction that proceeds at the atomic level, the surface roughness of the machined surface is very small compared to conventional hole machining by electric discharge machining. After forming the trench, the protective film 12 attached to the side wall of the trench 11 can be easily removed by wet etching or the like.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of a fine trench processing machine to which a first embodiment of the present invention is applied.

FIG. 2 is a schematic structural view of a main part of the first embodiment of the present invention.

FIG. 3 is a schematic structural view of a main part of a second embodiment of the present invention.

FIG. 4 is a schematic structural diagram of a main part of a third embodiment of the present invention.

FIG. 5 is a schematic structural view of a main part of a fourth embodiment of the present invention.

FIG. 6A is a system configuration diagram of a conventional fine hole electric discharge machine, and FIG. 6B is a diagram provided for explaining the problem.

[Explanation of symbols]

 10 Work Material 11 Trench 12 Protective Film 20 Feed Mechanism 21 Processing Electrode (Anode Electrode) 30 Holder Electrode (Cathode Electrode) 31 High-Frequency Power 40 Vacuum Tank 50 Reactive Gas 60 Plasma Region 70 Laser Light Source 71 Optical Fiber 75 Light-Assisted Reaction Region

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaru Hattori 1-1-1, Showa-cho, Kariya city, Aichi prefecture Nihon Denso Co., Ltd.

Claims (6)

[Claims] 1. An ultrafine wire-shaped processing member having a tip portion, and a feeding means for arranging the processing member facing a material to be processed and feeding the processing member while keeping a constant distance from an etching bottom surface of the material to be processed. And a region between the tip of the processing member and the material to be processed, in a region between the reaction gas supply means for supplying a reaction gas and the tip of the processing member and the material to be processed, A fine trench processing machine comprising: an activation unit that forms an activation region that decomposes and dissociates a reaction gas. 2. The processing member is composed of a conductor, and the activating means forms a plasma region between the processing member and the material to be processed, and decomposes and dissociates the reaction gas in the plasma region. Item 1. A fine trench processing machine according to Item 1. 3. The processing member is composed of an optical waveguide, and the activating means irradiates the material to be processed with light from the tip of the optical waveguide, and decomposes and dissociates the reaction gas by the light. The fine trench processing machine according to claim 1, wherein: 4. The fine trench processing machine according to claim 2, wherein the processing member formed of the conductor has an insulating material coated on the barrel side wall. 5. The fine trench processing machine according to claim 1, wherein a discharge port for blowing the reaction gas toward the material to be processed is provided at the tip of the processing member. 6. An ultrafine wire-shaped processing member that forms a region for locally decomposing / dissociating a reaction gas between the tip portion and the processing material is disposed facing the processing material, and the processing member is disposed. The material to be processed is locally etched and removed while maintaining a constant distance from the etching bottom surface of the material to be processed, and the reaction product of the reaction gas generated in the decomposition / dissociation region and the material to be processed is processed. Fine trench processing method characterized by sequentially depositing on etched sidewalls of material