JPH09283495A - Electrode and discharge-generating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of impurities such as phosphorus and boron and metals, which are sometimes harmful in a semiconductor manufacturing process by including a thermal donor in silicon which constitutes an electrode. SOLUTION: An electrode 11 is made of silicon and is formed in the shape of a pin. A thermal donor 12, including an oxygen donor, gives free electrons to silicon. It also gives a conductivity to silicon as impurities such as phosphorus and boron do. The electrode 11 includes the thermal donor 12, not including the other impurities (impurities such as phosphorus and boron which give a conductivity). When the electrode 11 is sputtered, it does not emit phosphorus, boron, etc., which are impurities that have a bad influence on the semiconductor manufacturing environment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode and a discharge generator.

[0002]

2. Description of the Related Art A conventional technique will be described by taking an ion generator used in a semiconductor device manufacturing line as an example. Static electricity is disliked in the semiconductor device manufacturing line. this is,
There are problems that the device is charged and deteriorates due to the discharge of static electricity, and dust in the atmosphere is adsorbed by the static electricity on the wafer forming the product to cause a defect. In order to control these static electricity, measures against static electricity in a semiconductor device manufacturing environment are indispensable. Therefore, an ion generator is used to generate ions and the generated ions are dispersed in a manufacturing environment to neutralize static electricity.
As an ion generator that can be easily and inexpensively applied to a wide manufacturing environment, there is a system that generates ions by applying a high voltage to electrodes to generate a discharge. And titanium, tungsten, stainless steel (for example, SUS303) etc. are generally used for the said electrode.

[0003]

However, in the above metal electrode, when a discharge is generated, the generated ions are sputtered and scraped by the generated ions, and the scraped material is released into the atmosphere. It Therefore, as the miniaturization of semiconductor devices further progresses in the future, in the manufacturing field such as the manufacturing process of semiconductor devices where the contamination is extremely disliked, the product is defective due to the metal emitted from the electrode for generating ions as described above. The problem of becoming.

In order to avoid them, the electrodes formed of silicon have been developed. However, since it is necessary for the silicon electrode to have conductivity, impurities such as phosphorus and boron that impart conductivity are usually added to the silicon electrode. Such a silicon electrode is scraped by the electrode itself being sputtered by the ions generated during the discharge, and the scraped material is released into the atmosphere. At that time, the impurities added to the electrodes are also released into the atmosphere. Especially, in the manufacturing process of a semiconductor device, these impurities cause pollution. That is,
In the semiconductor device manufacturing process, the concentration of impurities is precisely controlled, and unintentional mixing of impurities hinders this control. Therefore, with further miniaturization in the future, the demand for impurity contamination will become stricter.

[0005]

SUMMARY OF THE INVENTION The present invention is an electrode and an electric discharge generating device which have been made to solve the above problems.

That is, the electrode is made of silicon and contains a thermal donor in the silicon. Alternatively, the electrode includes a conductor and a silicon layer formed on the surface of the conductor, and the silicon layer contains a thermal donor.

The electrode is made of silicon containing a thermal donor, or since a silicon layer containing a thermal donor is formed on the surface, conductivity can be obtained by the thermal donor. Moreover, when electric discharge is generated in the electrode, the generated substances are silicon and oxygen even if the electrode is sputtered and scraped off, for example, phosphorus, boron, etc. which may be harmful in the manufacturing process of the semiconductor device. It does not generate impurities or metal. Therefore, the electrode can be used as an electrode for generating a discharge in an atmosphere where the contamination is extremely disliked, such as a manufacturing process of a semiconductor device.

On the other hand, the discharge generator is a device for causing a discharge phenomenon between electrodes, and the surface of the electrode is made of at least silicon, and the silicon contains a thermal donor.

In the above-mentioned discharge generator, since the surface of the electrode for generating the discharge phenomenon is made of at least silicon, and this silicon contains a thermal donor, the electrode is made conductive by the thermal donor. Then, when a discharge is generated in the electrode, even if the electrode is sputtered and scraped, the generated substances are silicon and oxygen, and for example, phosphorus, boron, etc. which may be harmful in the manufacturing process of the semiconductor device. It does not generate impurities or metals. Therefore, the discharge generating device can be used in a manufacturing field such as a semiconductor device manufacturing process in which contamination is extremely disliked. As the discharge generator capable of having such a structure, there are, for example, an ion generator used as a countermeasure against static electricity, a dry etching device using plasma, and the like.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION An example of the first embodiment of the present invention will be described.
This will be described with reference to FIG. In the figure, an electrode used in an ion generator is shown as an example. In FIG. 1, (1) shows a schematic perspective view, and (2) shows a schematic partial enlarged view of a cross section of an electrode.

As shown in FIG. 1, the electrode 11 is made of silicon and is formed in a needle shape. The silicon is made of, for example, single crystal silicon, and is, for example, 1 × 10 ¹⁶ pieces / cm 2.
^The thermal donor 12 is included in a concentration of about ³ . The resistivity of this silicon is about 0.5 Ωcm. The thermal donor 12 also contains an oxygen donor, which gives free electrons to silicon, and gives conductivity to silicon like impurities such as phosphorus and boron.

The electrode 11 contains the thermal donor 12 and does not contain any other impurities (for example, impurities that impart conductivity such as phosphorus and boron). Therefore, when this electrode 11 is sputtered, impurities such as phosphorus and boron that adversely affect the manufacturing environment of the semiconductor device are not emitted from this electrode 11.

Next, a method of manufacturing the electrode 11 will be described.
First, a silicon ingot containing oxygen is manufactured.
For example, Czochralski commonly used in semiconductor device manufacturing (hereinafter referred to as CZ, CZ is an abbreviation for Czohralski)
A silicon ingot is manufactured by a method (also known as a melt-pulling method). With this CZ method, generally, a highly pure product can be obtained. Further, since the melt of silicon is put in the quartz crucible, oxygen is dissolved in the melt of silicon. Therefore, the silicon ingot also contains oxygen. Generally, 1 x 10 in silicon melt
^{About 18} / cm ³ oxygen atoms are contained. In order to impart conductivity to silicon, impurities such as phosphorus and boron that are usually added are not added.

After that, the silicon ingot is processed into a desired shape, and then the silicon ingot is subjected to 10 ° C. in a nitrogen atmosphere at 450 ° C.
A heat treatment for leaving for 0 hours is performed. For this heat treatment, for example, a resistance heating type heat treatment furnace is used, and the atmosphere thereof is kept in a clean state so as to be used in the manufacturing process of the semiconductor device in order to prevent the molded silicon from being contaminated. As a result, thermal donors are generated in the molded silicon at a concentration of about 1 × 10 ¹⁶ pieces / cm ³ , and the resistivity of the molded silicon decreases to about 0.5 Ωcm. In this way, a conductivity that can be used as an electrode is obtained. The temperature of the heat treatment is not limited to 450 ° C., and may be any temperature at which a thermal donor is generated in silicon. Generally, if the temperature is not higher than 300 ° C, the thermal donor is not generated, and if the temperature exceeds 600 ° C, the thermal donor disappears. Therefore, the heat treatment temperature is 30
It is necessary to set a predetermined temperature within the range of 0 ° C to 600 ° C, preferably 400 ° C to 500 ° C. Then, the molded silicon is processed into a predetermined electrode shape.

The electrode thus formed does not include impurities such as phosphorus and boron, which may be harmful in the manufacturing process of the semiconductor device, and contaminants such as metal, in the electrode itself.

Next, an example of the second embodiment will be described with reference to FIG. In the figure, an electrode of a dry etching apparatus is shown as an example. In FIG. 2, (1) shows a schematic perspective view,
(2) shows a schematic partial enlarged view of the cross section of the electrode.

As shown in FIG. 2, the electrode 21 is made of silicon and has a disk shape. The silicon is composed of, for example, single crystal silicon, and the thermal donor 12 has a concentration of about 1 × 10 ¹⁶ pieces / cm ^{3 in the} single crystal silicon.
Is included.

The electrode 21 contains the thermal donor 12 and does not contain any other impurities (for example, impurities such as phosphorus and boron that give conductivity). Therefore, when the electrode 21 is sputtered, impurities such as phosphorus and boron that adversely affect the manufacturing environment of the semiconductor device are not emitted from the electrode 21.

A method of manufacturing the electrode 21 will be described. First, a silicon ingot containing oxygen is manufactured. For example, magnetic Czochralski (hereinafter referred to as MCZ, which is generally used in semiconductor device manufacturing, is
A silicon ingot is manufactured by a magnetic abbreviation of Magnetic Czohralski (also known as a magnetic field application melting and pulling method).
With this manufacturing method, a higher purity can be obtained as compared with the general CZ method. Further, since the melt of silicon is put into a quartz crucible having high purity such as synthetic quartz, the purity of silicon can be further increased. in this case,
The oxygen concentration contained in silicon is 2 × 10
It will be about ¹⁷ pieces / cm ³ . It should be noted that impurities such as phosphorus and boron, which are added to give conductivity to silicon, are not added. In this way, an extremely high-purity silicon ingot containing oxygen as appropriate can be formed.

After that, the silicon ingot is processed into a desired shape and then heat treated by leaving it in a nitrogen atmosphere at 450 ° C. for 100 hours in the same manner as in the manufacturing method described in the first embodiment. As a result, thermal donors were generated in the molded silicon at a concentration of about 1 × 10 ¹⁶ pieces / cm ³ , and the resistivity of the molded silicon was 0.5 Ωcm.
To a lesser extent. The heat treatment temperature here is in the same range as described in the first embodiment. Then, the molded silicon is processed into a predetermined electrode shape.

As described above, in the manufacturing method of forming the electrode from the silicon ingot, the high purity silicon can be obtained relatively easily by forming the silicon ingot. Moreover, the impurities (such as phosphorus and boron) contained in the silicon ingot are extremely small. Therefore, the electrode 21 formed from this silicon ingot
The electrode itself does not contain impurities such as phosphorus and boron, which may be harmful in the manufacturing process of the semiconductor device, and contaminants such as metals.

In the above description of the first and second embodiments, the single crystal silicon electrodes 11 and 21 have been described.
1, 21 may be made of, for example, polycrystalline silicon, and the thermal donor may be contained in the same as the above. Further, the concentration of the thermal donor contained in silicon forming the electrodes 11 and 21 is not limited to 1 × 10 ¹⁶ pieces / cm ³ described above as long as the electrodes 11 and 21 do not lose the conductivity. It can be more or less than that.

Next, an example of the third embodiment of the present invention will be described with reference to FIG.
It will be explained by. In the figure, an electrode used in an ion generator is shown as an example. In FIG. 3, (1) shows a perspective partial broken sectional view, and (2) shows a schematic partially enlarged view of a cross section of the electrode.

As shown in FIG. 3, the electrode 31 is composed of a needle-shaped conductor 32 and a silicon layer 33 covering the conductor. The conductor 32 is made of a metal material such as tungsten or stainless steel. On the other hand, the silicon layer 33 is made of, for example, polycrystalline silicon,
This polycrystalline silicon contains the thermal donor 12 at a concentration of about 1 × 10 ¹⁶ pieces / cm ³ .

The silicon layer 33 of the electrode 31 contains the thermal donor 12 and contains no other impurities. Therefore, when the silicon layer 33 is sputtered, impurities such as phosphorus and boron that adversely affect the manufacturing environment of the semiconductor device are contained in the silicon layer 33.
Not emitted from.

An example of a method of manufacturing the electrode 31 will be described. First, the needle-shaped conductor 32 is formed by a known method. Next, the silicon layer 33 is formed on the surface of the conductor 32 by, for example, the CVD method. After that, oxygen is introduced into the silicon layer 33 by, for example, plasma doping. The silicon layer 33 is preferably formed of single crystal silicon, but may be formed of polycrystalline silicon.

Then, heat treatment is performed by leaving it in a nitrogen atmosphere at 450 ° C. for 100 hours in the same manner as in the manufacturing method described in the first embodiment. As a result, thermal donors are generated in the silicon layer 33 at a concentration of about 1 × 10 ¹⁶ pieces / cm ³ , and the resistivity of the silicon layer 33 decreases to about 0.5 Ωcm. The temperature range of the heat treatment in this case is
This is similar to that described in the first embodiment.

The electrode 31 thus formed does not include impurities such as phosphorus and boron, which may be harmful in the manufacturing process of the semiconductor device, and contaminants such as metal, in the electrode itself.

Next, an example of the fourth embodiment will be described with reference to FIG. In the figure, an electrode used in an ion generator is shown as an example. In FIG. 4, (1) shows a perspective partial broken sectional view, and (2) shows a schematic partially enlarged view of a cross section of the electrode.

As shown in FIG. 4, the electrode 41 comprises a disc-shaped conductor 42 and a silicon layer 43 covering the conductor. The conductor 42 is made of a metal material such as tungsten or stainless steel. on the other hand,
The silicon layer 43 is made of, for example, polycrystalline silicon, and the thermal donor 12 is contained in the polycrystalline silicon at a concentration of about 1 × 10 ¹⁶ pieces / cm ³ .

The silicon layer 43 of the electrode 41 contains the thermal donor 12, but does not contain any other impurities (for example, impurities such as phosphorus and boron that give conductivity). Therefore, when the silicon layer 43 is sputtered, impurities such as phosphorus and boron that adversely affect the manufacturing environment of the semiconductor device are contained in the silicon layer 4.
Not released from 3.

An example of a method of manufacturing the electrode 41 will be described. First, the disk-shaped conductor 42 is formed by a known method. Next, the silicon layer 43 is formed on the surface of the conductor 42 by, for example, the CVD method. After that, oxygen is introduced into the silicon layer 43 by, for example, plasma doping. The silicon layer 43 is preferably formed of single crystal silicon, but may be formed of polycrystalline silicon.

Then, heat treatment is performed by leaving it in a nitrogen atmosphere at 450 ° C. for 100 hours in the same manner as in the manufacturing method described in the first embodiment. As a result, thermal donors are generated in the silicon layer 43 at a concentration of about 1 × 10 ¹⁶ pieces / cm ³ , and the resistivity of the silicon layer 43 decreases to about 0.5 Ωcm. The electrode 41 thus formed is
The electrode itself does not contain impurities such as phosphorus and boron, which may be harmful in the manufacturing process of the semiconductor device, and contaminants such as metal.

In the description of the above third and fourth embodiments, the thermal donor 12 contained in the silicon layers 33 and 43 forming the electrodes 31 and 41 is the same as long as the silicon layers 33 and 43 do not lose their conductivity. 1 × 10 ¹⁶ pieces / c mentioned above
The concentration is not limited to about m ³ and may be higher or lower than that.

In the manufacturing methods described in the first to fourth embodiments, it is possible to control the generation amount of the thermal donor 12 by changing the temperature and time of the heat treatment. Therefore, the resistivity (or conductivity) of silicon
Therefore, it is possible to obtain an electrode having a predetermined resistivity (or conductivity). Furthermore, the resistivity (or conductivity) can be controlled by changing the oxygen concentration in silicon.

The electrodes manufactured by the manufacturing methods described in the above-described first to fourth embodiments can be used in a manufacturing field in which contamination is extremely disliked, such as a semiconductor device manufacturing process. It can be applied to an electrode of an ion generator used for the above, an electrode of a dry etching apparatus using plasma, and the like.

Next, an example of an ion generator as the discharge generator of the present invention will be described with reference to the schematic configuration diagram of the main part of FIG.

As shown in FIG. 5, the ion generator 61
In the conventional ion generator, the electrode 62a and the electrode 62b are formed of silicon containing a thermal donor (not shown). Here, the configuration of the ion generator 61 will be briefly described. This ion generator 6
1 includes an electrode 62a and an electrode 62 for causing a discharge.
and b are arranged at a predetermined interval. The electrodes 62a and 62b are attached to the insulating electrode holding portions 63a and 63b, respectively, and the electrode holding portions 63a and 63b are attached to the main body 64, respectively. Further, a power source 65 for generating corona discharge between the power sources is connected to each of the electrodes 62a and 62b. Although not shown, a switch and a capacitor are connected between the electrode 62a and the electrode 62b and the power supply 65.

The electrodes 62a and 62b are, for example, needle-like ones having a length of about 5 mm, and are made of silicon containing a thermal donor (not shown) at a concentration of about 1 × 10 ¹⁶ pieces / cm ^3. It was done.

In the ion generator 61, a high voltage of alternating current (AC) or direct current (DC or pulse DC) is applied to each electrode 62a and electrode 62b from a power source 65 to generate an electrode 62.
Ions are generated by generating a corona discharge between a and the electrode 62b.

When such an ion generator 61 is used in a semiconductor device manufacturing environment, for example, the ion generator 61 is attached to the ceiling of the work environment, and is generated between the electrodes 62a and 62b of the ion generator 61. Ions generated by the generated corona discharge are scattered in the work environment. The ions neutralize the static electricity. Therefore, deterioration of the device due to electrostatic discharge and electrostatic attraction of dust in the atmosphere are suppressed, so that it is possible to suppress the occurrence of defects caused by these. At that time, the electrode 62a and the electrode 62 are discharged during discharge.
b is removed by sputtering and released into the atmosphere. However, since the electrodes 62a and 62b do not contain impurities such as phosphorus and boron, which may be harmful to metal or semiconductor manufacturing, such metals and impurities are not emitted and contamination by these occurs. Absent.

Next, an example of a dry etching apparatus as a discharge generating apparatus of the present invention will be described with reference to the schematic configuration diagram of FIG. In the figure, a parallel plate type reactive ion etching apparatus is shown as an example of the dry etching apparatus.

As shown in FIG. 6, the dry etching apparatus 71 is a conventional dry etching apparatus in which a silicon electrode 73 containing a thermal donor (not shown) is formed on the surface of a cathode electrode 72 and a surface of an anode electrode 74. A silicon electrode 75 including a thermal donor (not shown) is formed on the substrate.

The outline of the structure of the dry etching apparatus 71 will be described below. The dry etching apparatus 71 is provided with a processing chamber 81 for processing the wafer 91.
A cathode electrode 72 is provided in the processing chamber 81. The cathode electrode 72 includes a metal electrode 76 and a silicon electrode 73 provided on the metal electrode 76. The silicon electrode 73 has, for example, a disk shape with a thickness of about 5 mm, and contains thermal donors at a concentration of about 1 × 10 ¹⁶ pieces / cm ³ . A wafer 91 to be etched is placed on the silicon electrode 73. On the other hand, the metal electrode 76 is made of, for example, an aluminum-based metal.
A power source 83 is connected to the cathode electrode 72 via a capacitor 82. In addition, the cathode electrode 72
A flow path (not shown) for flowing the coolant is provided inside the cathode, and the cathode A 72 can be cooled by circulating the coolant A in the flow path. Cold water, for example, is used as this refrigerant.

Further, inside the processing chamber 81, the caustic
An anode electrode 74 is provided above the cathode electrode 72.
Is placed. The anode electrode 74 and the metal electrode 77
Silicon electrode 75 installed under the metal electrode 77
Consists of The silicon electrode 75 has, for example, a thickness of 5
mm-shaped disk with 1 × 10 thermal donors ¹⁶
Pieces / cm^ThreeIncluded in the degree of concentration. On the other hand, the above metal
The electrode 77 is made of, for example, an aluminum-based metal. Soshi
The anode electrode 74 is connected to the ground 84.
You. Further, an etching gas is introduced into the processing chamber 81.
Gas supply system (in the drawing, the gas supply system
85) is connected, and the gas in the processing chamber 81 is further connected.
Gas exhaust system for exhausting the
86 is connected).

The dry etching apparatus 71 has a power source 8
High frequency power is applied to the cathode electrode 72 from 3 to generate discharge between the cathode electrode 72 and the anode electrode 74 to generate plasma.

Such a dry etching apparatus 71 is
For example, when used in the manufacturing process of a semiconductor device, the wafer is etched by the plasma generated between the cathode electrode 72 and the anode electrode 74. At that time, during discharge, the exposed portion of the cathode electrode 72 and the surface of the anode electrode 74 are scraped by sputtering, and the sputtered substance is released into the etching atmosphere. However, the cathode electrode 72 and the anode electrode 7
Since 4 does not contain impurities such as phosphorus and boron or metals that may be harmful in the manufacturing process of the semiconductor device,
There is no release of such impurities or metals and no contamination by them occurs.

[0048]

As described above, according to the electrode of the present invention, since the silicon layer containing the thermal donor is formed or the silicon layer containing the thermal donor is formed on the surface, the silicon is conductive by the thermal donor. You can get sex. Then, even if the electrode is sputtered and scraped off, the substances generated by this sputtering are silicon and oxygen, for example, to obtain conductivity such as phosphorus and boron which may be harmful in the manufacturing process of the semiconductor device. It does not generate impurities or metal.

Further, according to the discharge generator of the present invention, since the electrode for generating the discharge phenomenon is the one whose surface is made of at least silicon and the thermal donor is contained in this silicon, this electrode is electrically conductive by the thermal donor. You can get sex. Then, even if the electrode is sputtered and scraped off, the substances generated by this sputtering are silicon and oxygen, for example, to obtain conductivity such as phosphorus and boron which may be harmful in the manufacturing process of the semiconductor device. It does not generate impurities or metals used for. Therefore, the discharge generator can be used in a manufacturing field such as a semiconductor device manufacturing process where contamination is extremely disliked. For example, the discharge generator is applied to an ion generator used as a countermeasure against static electricity and a dry etching device using plasma. It is possible to

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a first embodiment relating to an electrode of the present invention.

FIG. 2 is an explanatory diagram of a second embodiment relating to the electrode of the present invention.

FIG. 3 is an explanatory diagram of a third embodiment relating to an electrode of the present invention.

FIG. 4 is an explanatory diagram of a fourth embodiment relating to the electrode of the present invention.

FIG. 5 is a schematic configuration diagram of a main part of the ion generator of the present invention.

FIG. 6 is a schematic configuration diagram of a dry etching apparatus of the present invention.

[Explanation of symbols]

 11 electrode 12 thermal donor

Claims (5)

[Claims] 1. An electrode made of silicon, characterized in that a thermal donor is contained in silicon constituting the electrode. 2. An electrode comprising a conductor and a silicon layer formed on the surface of the conductor, wherein the silicon layer contains a thermal donor. 3. A discharge generator for causing a discharge phenomenon between electrodes, wherein the surface of the electrode is made of at least silicon, and the silicon contains a thermal donor. 4. The discharge generator according to claim 3, wherein ions are generated by a discharge phenomenon caused between the electrodes. 5. The discharge generator according to claim 3, wherein plasma is generated by a discharge phenomenon caused between the electrodes, and the object to be etched is etched by the plasma.