JPH1192972A - Manufacturing method of electrode for plasma apparatus and electrode for plasma apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode which can be efficiently machined at a low cost at the time of forming a large number of fine holes for passing gas therethrough in the electrode for a plasma apparatus and with which a device of excellent quality can be manufactured when used as the electrode. SOLUTION: When a large number of fine holes (a),... are formed in the electrode plate 1, prepared holes of 0.1 to 1.0 mm diameter are formed by electric discharge machining or laser machining at machining speed of >=3 mm/min and then the prepared holes are further machined in a range of 0.005 to 0.2 mm plus the original hole diameter by diamond machining at machining speed of <3 mm/min to complete the fine holes (a). In this case, silicon, carbon, aluminum and silicon carbide are preferably used as a raw material of the electrode plate 1, preferable number of the fine holes(a),... is 150 to 6000 and resistance value of <=1 Ωcm is preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved method for manufacturing an electrode for a plasma device having fine holes used in, for example, a plasma dry etching device and the like, and to an electrode manufactured by the method.

[0002]

2. Description of the Related Art Conventionally, for example, in a plasma dry etching apparatus or the like, a semiconductor wafer is mounted on a plane electrode connected to a high frequency power supply in a reaction chamber, and a large number of fine holes are formed in a counter electrode facing the semiconductor wafer. A technique is known in which a reactive gas is introduced into a reaction chamber through the fine holes, and plasma is generated between a plane electrode and a counter electrode to perform an etching process.

[0003] As a method of processing a large number of fine holes in the counter electrode, for example, an ultrasonic processing method, an electric discharge processing method, a laser processing method, a so-called diamond processing method and the like are known.

[0004] Here, these processing methods will be briefly described. First, in the ultrasonic processing method, a tool that vibrates ultrasonically is pressed against a workpiece through an abrasive slurry, and the ultrasonic vibration is applied through the abrasive grains. It is a method of processing a workpiece,
Specifically, a processing jig called a horn with a stainless steel pin set up corresponding to the drilling position is attached to the ultrasonic processing machine so that the vibration from the ultrasonic transmitter is transmitted to the processing jig. Ultrasonic vibration while flowing the abrasive slurry, in which abrasive powder such as diamond, silicon carbide, boron carbide, etc. is dispersed in water, etc., onto the pin tip give.

[0005] Then, the abrasive grains present between the workpiece and the pin are polished by the ultrasonic vibration and the workpiece is polished. When the pin is processed and fed, a hole slightly larger than the pin diameter is formed in the workpiece. .

Next, in the electric discharge machining method, a workpiece and a machining electrode are opposed to each other with a small gap, and a short-time pulsed arc discharge is repeated through an insulating machining fluid to process the workpiece. Specifically, the tip of the machining electrode having a predetermined diameter is brought close to the workpiece and opposed at a predetermined gap, and the machining fluid is ejected from the tip of the machining electrode, or after the workpiece is immersed in the machining fluid. A pulse discharge is generated between the machining electrode and the workpiece.

[0007] Then, the surface of the workpiece facing the machining electrode is melted by the discharge, and when the machining electrode is machined, a hole slightly larger than the diameter of the machining electrode is formed in the workpiece.

Next, the laser processing method is a processing method of irradiating a workpiece with a laser beam to melt and sublimate an irradiated portion. As a laser oscillation source, carbon dioxide, YAG or the like is generally used. .

[0009] Next, the diamond machining method is a machining method using a machine tool such as a diamond tool, in which a workpiece is pierced using a diamond tool having a predetermined diameter.

[0010]

By the way, each of the above-mentioned processing methods has its own characteristics. Particularly, when applied to the processing of fine holes in an electrode for a plasma apparatus, the following processing methods are used. There was a defect.

That is, first, the ultrasonic machining method has an advantage that, when a large number of holes are machined, a horn provided with a large number of pins can be simultaneously drilled in one machining, but a large number of holes are machined. The initial investment to make a horn with a pin is required, and when drilling into a workpiece,
Accordingly, the pins of the processing jig also wear, so that the diameter of the processing hole gradually decreases, and the processing accuracy decreases.

Further, when the pins of the processing jig are worn, the metal abrasion powder adheres to the processing surface around the hole. Thereafter, this electrode is attached to a plasma apparatus and subjected to etching or the like, so that semiconductors such as ICs and LSIs are formed. In the case of manufacturing a device, there is a problem that the device characteristics are degraded due to impurities or particles and the device yield is deteriorated.

Next, in the case of the electric discharge machining method, since the high energy of electric discharge is directly used for machining, the machining speed is high.
In addition, it has the advantage of being able to save labor and can be processed at low cost, but on the other hand, due to repeated melting and solidification, the processed surface of the hole periphery becomes severe unevenness after processing, and then this electrode is attached to the plasma device to process the device At times, it becomes a factor of particle generation which is a great enemy of the device. In particular, when the processing speed is increased, such a tendency becomes remarkable, and eventually the processing speed has to be reduced.

In addition, a processing damage layer is generated near the hole due to the high temperature during processing, and then, during use while being attached to a plasma apparatus, the corrosion of the electrode becomes non-uniform due to the processing damage layer, and the quality of a device to be manufactured is deteriorated. Is not stable. That is, when the electrode for a plasma device is repeatedly used, the electrode itself generally undergoes corrosion, and if the corrosion proceeds uniformly throughout, the device does not have much adverse effect, but if there is a processing damage layer, The corrosion becomes non-uniform and adversely affects the fabricated device.

Next, in the case of the laser processing method, for example, NC
The use of a control device allows labor saving and cost reduction, and has the advantage of high-speed machining. However, the machining is less stable than other machining methods. There is.

Further, burrs are easily generated on the surface opposite to the laser irradiation surface, and a processing damage layer is formed around the hole. Therefore, the quality of the device is not stabilized during use after attaching the electrode to a plasma apparatus. Also, there is a problem that the yield is reduced. Then, similarly to the case of electric discharge machining, when the machining speed is increased, such inconvenience becomes remarkable, so that the machining speed has to be reduced after all.

Next, in the case of the diamond processing method, since an unmanned machine tool can be used, there is an advantage that the cost can be reduced. On the other hand, when a diamond tool having a small diameter is used, the diamond reaction is performed by the processing reaction force. There is a problem that the tool is liable to be broken or the like, which causes a decrease in accuracy and that processing cannot be performed at a very high speed.

In view of the above, according to the present invention, in forming an electrode by forming fine holes for gas passage in an electrode for a plasma apparatus, the above-mentioned various problems can be corrected, and the electrode can be efficiently manufactured at low cost. It is an object of the present invention to provide a method for manufacturing an electrode for a plasma apparatus and a method for manufacturing an electrode for a plasma apparatus, which does not generate impurities or particles when used as an electrode and can produce a high-quality device.

[0019]

According to the present invention, there is provided a method of manufacturing an electrode for a plasma device having a large number of fine holes for passing a reaction gas, the method comprising the steps of: After drilling a large number of pilot holes having a diameter smaller than that of the fine holes at a high processing speed higher than a predetermined speed, the peripheral edge of the lower holes is processed at a low processing speed lower than the predetermined speed to finish the pilot holes into fine holes. I did it.

As described above, if the initial processing is performed at a high speed and then the processing is performed at a low speed, a large number of fine holes can be processed relatively efficiently, and the processed surface of the hole periphery can be finely finished. When used, the quality of the device to be manufactured can be improved.

That is, the reason why the drilling is initially performed at a processing speed higher than the predetermined speed is that if the speed is too low, it takes a long time to drill a large number of fine holes, leading to an increase in cost. In general, high-speed processing often causes unevenness or a processing damage layer around a hole, and causes various problems when used as an electrode for a plasma device.

Then, after that, finish processing is performed at a processing speed lower than a predetermined speed, and unevenness or a processing damage layer generated around the hole is removed by a low-speed processing means, so that generation of particles when used as an electrode or processing damage layer is performed. And to improve the quality of the manufactured device. At this time, if the low-speed machining is set to a speed equal to or higher than a predetermined speed,
The processed surface of the hole periphery cannot be finished with high accuracy, and various problems when used as an electrode cannot be prevented.

According to a second aspect of the present invention, the high-speed machining speed is 3 mm.
/ min or higher, and the low-speed processing speed was lower than 3 mm / min. Here, as a processing means for processing at a high processing speed of 3 mm / min or more, for example, electric / chemical processing methods such as electric discharge machining, ion beam machining, electron beam machining, and laser machining can be applied. As a processing means at a speed lower than 3 mm / min, for example, a polishing / grinding method using a drill tool or the like can be applied.

If the prepared hole is processed at a high speed by an electrochemical and chemical processing method, and the portion where the prepared hole is formed is machined with a drill tool or the like, the processing reaction force applied to the drill tool or the like is reduced and the breakage is caused. The machining time can be drastically shortened as compared with the case of directly machining a portion without a prepared hole with a drill tool or the like.

In claim 3, the high-speed machining is electric discharge machining or laser machining, and the low-speed machining is diamond machining.
Here, if the high-speed machining is electric discharge machining or laser machining, machining can be performed at a high speed, manpower can be saved, and the configuration can be made relatively inexpensively. In addition, if diamond processing is used for low-speed processing, it is possible to configure accurately and simply.

In the present invention, the diameter of the prepared hole formed by high-speed machining is set to 0.1 to 1.0 mm. Here, if the diameter of the prepared hole is 0.1 mm or less, the reaction force applied to a drill tool or the like at the time of low-speed machining cannot be reduced, and, for example, in the case of electric discharge machining, the strength of the machining electrode is reduced. Run out. On the other hand, if the thickness is 1.0 mm or more, the uniformity of the gas passing therethrough when used by attaching to a plasma apparatus is impaired, and the yield in the device process is reduced. Therefore,
It is desirable that the range of the pilot hole diameter be 0.1 to 1.0 mm.

According to the fifth aspect, the diameter of the hole to be machined by low-speed machining is set to the diameter of the pilot hole plus 0.005 to 0.2 mm.
Here, if the diameter of the pilot hole is 0.005 mm or less,
Unable to completely remove irregularities and burrs on the machined surface around the hole, leaving particles and impurities to be generated, and if the pilot hole diameter is set to 0.2 mm or more, the reaction force applied to the drill tool etc. It becomes too large and the merit of providing a pilot hole is reduced. Therefore, if the thickness is set in this range, drilling and the like can be performed accurately and smoothly.

According to a sixth aspect of the present invention, there is provided an electrode for a plasma device having fine holes formed by the above-described manufacturing method.
It was composed of any one of silicon, carbon, aluminum, and silicon carbide.

This is because, when other materials are used as electrodes of a plasma device, they tend to become heavy metals and other impurities that cause deterioration of device characteristics when manufacturing a semiconductor device. In this case, when the wafer to be processed is semiconductor silicon, the same material as the semiconductor material is preferable if silicon is particularly selected from the above materials.

According to a seventh aspect of the present invention, the number of the fine holes is set to 150
６6000 holes. If the ratio is out of this range, the uniformity of the gas ejected through the fine holes is impaired, which is inconvenient in device fabrication.

According to claim 8, the material of the electrode is 1 Ωcm
The following specific resistance was used. This is because, for example, when using electric discharge machining, the electrode (workpiece) also needs to be a conductor, and when silicon is used as the material, if single crystal silicon having a specific resistance of 1 Ωcm or less is used, the machining is performed. It will be easier. When the material is silicon, such a resistance value can be easily controlled by adjusting the addition amount of a dopant such as boron or phosphorus.

[0032]

Next, embodiments of the present invention will be described, but the present invention is not limited to these embodiments. The present invention is a technique for forming a large number of fine holes a,... In, for example, an electrode plate 1 for a plasma apparatus as shown in FIG. The screws 16 are attached to the dry etching apparatus 10 through the attachment holes s and are used.

That is, the etching apparatus 10 includes a chamber 11 to which a gas introduction system 12 and a discharge system 13 are connected.
And a flat electrode 14 installed in the chamber 11 and connected to a high frequency power supply, and an electrode plate 1 opposed thereto. The electrode plate 1 is provided with an internal gas container 15 communicating with a gas introduction system 12. The reaction gas is attached to the lower surface through the attachment holes s,..., And is sent downward to the internal gas container 15 through the gas introduction system 12 through the fine holes a,.

Then, the semiconductor wafer W is placed on the flat electrode 14 to which the high-frequency power is applied, and a discharge is generated between the semiconductor wafer W and the counter electrode plate 1 so that the surface of the semiconductor wafer W is etched. ing.

Here, if the fine holes a,... Of the electrode plate 1 are too large, the uniformity of the ejected gas is impaired and the etching process is not performed uniformly. If the small holes a are too small, processing becomes difficult. Also, if irregularities occur on the processing surface at the peripheral edge of the fine holes a,..., It causes particles to be generated, and if a processing damage layer occurs, the electrode plate 1 becomes non-uniformly corroded and plasma is generated non-uniformly.

Accordingly, the present invention provides a method of manufacturing the electrode plate 1 with fine holes a,.
Are efficiently formed with a predetermined hole diameter, and at the same time, are intended to be micro holes a, which do not cause inconvenience to the plasma processing,
The electrode plate 1 was manufactured by the following method.

First, as a material of the electrode plate 1, silicon,
One of carbon, aluminum, and silicon carbide is selected. Here, to select from these materials,
This is because other materials contain a lot of heavy metals and other impurities which are likely to cause a malfunction when manufacturing a semiconductor device. Among these, it is most preferable to select silicon, in particular, when the semiconductor wafer W to be processed is single-crystal silicon, since the same material is used.

The material thus selected is set on a high-speed processing machine having a processing speed of 3 mm / min or more. Where 3mm / min
The reason why the processing speed is set as described above is that if the processing speed is lower than this, the processing time is increased and the cost is increased. Conventionally, such high-speed machining has caused damage to the machined surface and caused particles and the like. In the present invention, however, such high-speed machining may be performed since low-speed machining is performed later. An electric discharge machine or a laser machine is suitable as a high-speed machine.

Here, an outline of the electric discharge machining operation will be described. When the electric discharge machining is selected, the machining machine may be of a type in which the material is immersed in a machining fluid for processing, or a type in which the machining fluid is ejected from the electrode.

First, an electrode for electric discharge machining suitable for a prepared hole to be formed in a material is prepared. At this time, an appropriate material such as copper, brass, or tungsten is selected as a material of the electrode for electric discharge machining. The diameter of the pilot hole is usually 0.1 mm or more and 1.0 mm or less. This is 0.1mm
If it is thinner, the strength of the electrode for electric discharge machining will be insufficient, and 1.0 mm
This is because when used as an electrode plate 1 for a plasma electrode to be manufactured, the uniformity of gas ejection is impaired.

The number of the fine holes a,.
It is preferable to make 00 holes. If the amount is more or less than this range, the uniformity of the gas ejected when used as the electrode plate 1 is impaired, and the yield of the device is reduced.

As the machining conditions of the electric discharge machining, conditions capable of uniformly and accurately drilling holes are appropriately selected. At this time, if the electric discharge machine is controlled by the NC, it is possible to save labor and to perform machining with high accuracy.

When electric discharge machining is performed, the material must be a conductive material.
It is desirable to adopt the following. For example, when the electrode material is silicon, the resistance value is controlled by adjusting the addition amount of a dopant such as boron or phosphorus.

Next, a case where laser processing is employed will be described. First, set the material on the laser processing machine,
Laser light from a laser transmitter, such as carbon dioxide, is applied to the position where the pilot hole is processed, and a pilot hole is drilled. At this time, processing conditions such as laser power and the like are appropriately selected and adjusted so that a pilot hole having the above-described diameter is formed. Further, such a processing machine is generally controlled by NC, and as in the case of electric discharge machining, cost can be reduced by labor saving.

When the pilot hole is formed by the high-speed machining,
Next, the periphery of the hole is machined at a machining speed lower than 3 mm / min. As this low-speed processing, for example, diamond processing using a diamond drill or the like is appropriate, and when performing high-speed processing of 3 mm / min or more in this diamond processing, a damaged layer is generated thickly due to thermal effects on the processing surface, In subsequent use, the yield of the device is reduced, and the diamond tool is frequently broken, which leads to an increase in cost.

For the diamond processing, a normal machining center or the like is used as a machine tool. Here, after the electrode plate material is set on the machine tool, it is necessary to accurately perform the diamond machining at the position of the prepared hole.In order to maintain good accuracy, for example, between the electric discharge machine and the diamond machining machine It is preferable to take measures such as sharing the set jig.

As a tool for performing diamond processing, a diamond tool having diamond abrasive grains or the like fixed to the tip by nickel electrodeposition or the like such as a normal super-steel drill tool may be used. What processed and formed the polycrystalline diamond etc. as a drill tool may be used.

The diameter of the fine holes a,... Formed by diamond processing is set to be not less than the diameter of the prepared hole plus 0.005 mm and not more than the diameter of the prepared hole plus 0.2 mm. If the thickness is less than 0.005 mm, irregularities or burrs formed in the prepared hole by high-speed processing remain and cause particles to be generated. The reaction force increases, and the diamond tool is liable to break.

Therefore, when the diameter is within the above range, the processing reaction force applied to the diamond tool is reduced, so that the diamond tool can be prevented from being broken and the processing speed can be drastically increased. Moreover, irregularities and burrs generated by high-speed processing,
The processing damage layer can be completely removed.

[0050]

Next, examples of the present invention will be described. First, the diameter 30
An ingot of 0 mm and 0.1 Ωcm single crystal silicon was prepared, and an electrode plate material having a thickness of 6 mm was sliced from the ingot and the outer periphery was processed to a diameter of 280 mm. At the outer periphery of this electrode plate material, screw 1
6, one mounting hole s with counterbore for mounting with
It was processed over two locations.

Next, this electrode plate material was set in an electric discharge machine, and a copper discharge electrode having a diameter of 0.45 mm was used.
A 650 pilot hole was subjected to electrical discharge machining at a processing speed of mm / min.

Thereafter, this electrode plate material was attached to a machining center, and diamond machining was performed at a machining speed of 2.5 mm / min at the same position as the prepared hole using a single crystal diamond tool having a diameter of 0.55 mm.

The electrode plate 1 with micro holes thus manufactured is
Attached to the plasma dry etching apparatus 10 as shown in FIG. 2, the CF ₄ gas sent from the gas introduction system 12 is ejected from the fine holes a,... Of the silicon oxide film was etched. As a result, no particles were generated, and the etching rate was uniform over the entire surface.

The present invention is not limited to the above embodiment. The above embodiment is an exemplification, and has substantially the same configuration as the technical idea described in the scope of the claims of the present invention. It is included in the technical scope of the invention.

[0055]

As described above, according to the present invention, when a large number of fine holes for passing a reaction gas are formed in an electrode for a plasma device, the processing speed is higher than a predetermined speed. By drilling a prepared hole in the hole and then finishing it into a fine hole at a processing speed lower than the predetermined speed, it is possible to efficiently process a fine hole of a predetermined diameter, and when using as a plasma device electrode, particles It is possible to prevent defects such as occurrence and to stabilize the quality of the manufactured device. The high-speed machining is preferably electric discharge machining or laser machining, and the low-speed machining is preferably diamond machining. Further, by setting the diameter of the prepared hole formed by high-speed processing to a predetermined range, each processing can be performed smoothly and gas can be passed uniformly.

When the diameter of the hole to be machined by low-speed machining is set within a predetermined range, irregularities on the machined surface at the periphery of the hole can be completely removed, and the generation of particles can be prevented. Processing reaction force can be reduced. Further, as in claim 6, the electrode for a plasma device is
If it is composed of any one of silicon, carbon, aluminum, and silicon carbide, it is unlikely to become an impurity in the device manufacturing process. Further, if the number of the fine holes is within a predetermined range, the uniformity of the gas can be ensured, and if the resistance of the electrode is equal to or less than the predetermined value to ensure the conductivity, the conductivity can be ensured. For example, it can be processed by electric discharge machining.

[Brief description of the drawings]

FIG. 1 is a plan view of an electrode plate according to the present invention.

FIG. 2 is an explanatory diagram of a plasma dry etching apparatus to which the present electrode plate is applied.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electrode plate, 10 ... Plasma dry etching apparatus, 11 ... Chamber,
12: gas introduction system, 13: exhaust system,
14: flat electrode, 15: internal gas container,
16: Screw, a: Micro hole,
s: mounting hole, W: semiconductor wafer.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kazuyoshi Tamura 2-13-1 Isobe, Annaka-shi, Gunma Prefecture Shin-Etsu Chemical Industry Co., Ltd.

Claims (8)

[Claims] 1. A method of manufacturing an electrode for a plasma device having a large number of fine holes for passing a reaction gas, comprising: A method of manufacturing an electrode for a plasma device, comprising: drilling at a speed, and processing the periphery of the prepared hole at a low processing speed lower than a predetermined speed to finish the prepared hole into the fine hole. 2. The method for manufacturing an electrode for a plasma device according to claim 1, wherein the high-speed processing speed is a processing speed of 3 mm / min or more, and the low-speed processing speed is a processing speed of less than 3 mm / min. A method for producing an electrode for a plasma device, which is characterized in that: 3. The method for manufacturing an electrode for a plasma device according to claim 1, wherein said high-speed machining is electric discharge machining or laser machining, and said low-speed machining is diamond machining. A method for manufacturing an electrode for a device. 4. The method for manufacturing an electrode for a plasma device according to claim 1, wherein a diameter of the prepared hole formed by the high-speed processing is 0.1 to 1.0 mm. A method for manufacturing an electrode for a plasma device. 5. The method for manufacturing an electrode for a plasma device according to claim 1, wherein the diameter of the hole processed by the low-speed processing is the diameter of the pilot hole plus the diameter of the pilot hole.
A method for producing an electrode for a plasma device, wherein the thickness is from 0.5 to 0.2 mm. 6. A method of manufacturing according to claim 1, wherein the material is silicon,
An electrode for a plasma device comprising any one of carbon, aluminum, and silicon carbide. 7. The electrode for a plasma device according to claim 6, wherein the number of the fine holes is from 150 to 6000. 8. The electrode for a plasma device according to claim 6, wherein a material of the electrode has a specific resistance of 1 Ωcm or less.