JPH06140127A - Ionizer discharge electrode - Google Patents

Abstract

PURPOSE:To provide an ionizer discharge electrode, optimum for use in a semiconductive clean room and moreover nondistructive even by the application of high voltage. CONSTITUTION:A bar 11, having the base material of polycrystal silicon, is provided; and in this bar 11, a conductive layer 12, having electric resistance lower than that of silicon base material, is formed on the outer peripheral surface of a part 11a' receiving high voltage from the contact piece of an ionizer, and silicon base material is exposed in the tip part 11b of the bar.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge electrode used in an ionizer.

[0002]

BACKGROUND OF THE INVENTION As disclosed in U.S. Pat. No. 3,585,448, an ionizer has a discharge electrode. By applying a high voltage to the discharge electrode, a corona discharge is caused at the tip of the discharge electrode, the air molecules near the tip are ionized, and positive ions and negative ions are generated. These ions float in the air and remove the static electricity generated on the surface of the object. That is, among the floating ions, ions having a polarity different from that of the static electricity are combined with the static electricity to neutralize the static electricity. The discharge electrode is generally formed of a metal material having excellent conductivity such as stainless steel, tungsten and titanium. The metal element at the tip of the discharge electrode scatters in the air with corona discharge. Therefore, when the ionizer is used in a clean room of a semiconductor manufacturing factory, the scattered metal atoms are mixed or adhered to the semiconductor, resulting in deterioration of semiconductor quality.

Therefore, a discharge electrode made of silicon has been developed. Since the scattering of silicon does not adversely affect the semiconductor manufacturing, the above problem is solved.

[0004]

However, since the above silicon has a high electric resistance and the contact resistance between the outer peripheral surface of the discharge electrode and the contact of the ionizer is also high, the discharge electrode may be damaged by cracks or the like. There was something that happened.

[0005]

The invention according to claim 1 was made to solve the above-mentioned problems, and the gist thereof is to provide a bar member having polycrystalline silicon as a base material, and in this bar member, an ionizer is used. Is characterized in that a conductive layer having a lower electric resistance than the polycrystalline silicon base material is formed on the outer peripheral surface of the portion that receives a high voltage from the contactor, and the polycrystalline silicon base material is exposed at the tip of the bar. It is located in the discharge electrode for the ionizer. The gist of the invention of claim 2 resides in the discharge electrode for an ionizer according to claim 1, wherein the conductive layer is formed of a reaction layer of a metal and a polycrystalline silicon base material. Claim 3
The gist of the invention resides in the discharge electrode for an ionizer according to claim 1, wherein the conductive layer is composed of a metal layer attached to the outer peripheral surface of the rod.

[0006]

In the discharge electrode according to any one of claims 1 to 3, a conductive layer having a lower electric resistance than that of the polycrystalline silicon base material is formed on the outer peripheral surface of the portion which receives a high voltage from the contact of the ionizer, so that the discharge electrode is damaged by the high voltage. Can be prevented. Also, since polycrystalline silicon is used, it has the conductivity required for corona discharge without adding impurities like single crystal silicon.
Corona discharge at the tip is possible without forming a conductive layer at the tip. Further, the polycrystalline silicon base material is exposed at the tip of the discharge electrode, and only silicon is scattered by the corona discharge at the tip, which does not adversely affect the semiconductor manufacturing. Further, in the discharge electrode according to claim 2, since the conductive layer is formed by the reaction layer of the metal and the polycrystalline silicon base material,
Unlike the simple coating of the base material with a film of a conductive material, even if heat generation and cooling of the discharge electrode are repeated, the conductive layer of the discharge electrode does not crack or peel due to thermal stress. Further, in the discharge electrode according to the third aspect of the invention, since the conductive layer is constituted by the metal layer attached to the outer peripheral surface of the rod, even if a mechanical shock is applied from the outside, the metal layer can prevent cracking. .

[0007]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the ionizer 1 has a cylindrical conductive casing 2 and a conductive connector 3 arranged inside the casing 2 coaxially with the casing 2. Both ends of the casing 2 have a pair of insulating members 4
The connector 3 is supported by the central portion of these insulating members 4. One end of the connector 3 is led out of the casing 2 and connected to an AC high voltage source (not shown). The casing 2 is grounded.

A plurality of circular openings 5 are formed in the casing 2 along the axial direction. A plurality of needle-shaped discharge electrodes 10 arranged in the axial direction are connected to the connector 3, and are electrically connected to the connector 3. Specifically, a hole is formed in the connector 3, and a ring-shaped contactor (not shown) is housed in this hole. The discharge electrode 10 is inserted into this hole, and the contact is in contact with the outer peripheral surface thereof. The tip of each discharge electrode 10 projects from the connector 3 and is arranged to face the opening 5 of the casing 2. When a high voltage is applied to the connector 3, corona discharge is generated between the tip of the discharge electrode 10 and the peripheral edge of the opening 5, and the molecules in the air are ionized.

A blower pipe 6 extending parallel to the casing 2 is attached to a portion of the outer periphery of the casing 2 opposite to the discharge electrode 10. The casing 2 and the blower pipe 6 are communicated with each other through a plurality of communication passages 7 arranged along the axial direction of the casing 2. One end of the blower pipe 6 is closed, and the other end is connected to the blower mechanism. Casing 2 from blower mechanism through blower pipe 6 and communication passage 7
The air sent to is discharged from the opening 5. By this air blow, the positive ions and the negative ions generated by the corona discharge near the opening 5 are carried far outside the casing 2.

As shown in FIG. 2, the discharge electrode 10 has a bar material 11 whose base material is high-purity polycrystalline silicon.
The bar 11 has a cylindrical base portion 11a and a conical tip portion 11b. A conductive layer 12 is formed on the entire outer peripheral surface and the base end surface of the base portion 11a. The conductive layer 12 is composed of a reaction layer of a metal such as gold or aluminum and polycrystalline silicon, and a metal layer outside the reaction layer. The thickness of the conductive layer 12 is preferably 100 μm or more. The base material of polycrystalline silicon is exposed at the tip 11b of the rod 11.

When a high voltage is applied to the outer peripheral surface of the specific portion 11a 'of the base portion 11a of the discharge electrode 10 via a contactor, corona discharge is generated between the tip portion 11b and the peripheral edge of the opening 5 of the casing 2. Occur. At this time, in the discharge electrode 10, a specific portion 11a 'that receives a high voltage from the contact of the ionizer.
Since the conductive layer 12 having a lower electric resistance than the silicon base material is formed on the outer peripheral surface of, the damage of the discharge electrode due to the high voltage can be prevented. Further, since polycrystalline silicon is used, electricity can be supplied to the extent necessary for corona discharge without adding impurities as in the case of single crystal silicon, and corona discharge at the tip 11b becomes possible. Further, only the base material of high-purity polycrystalline silicon is exposed at the tip 11b of the discharge electrode.
Since only silicon is scattered by the corona discharge in (b), it does not adversely affect semiconductor production in a clean room. Further, in the discharge electrode 10, since the conductive layer 12 is formed of the reaction layer of metal and polycrystalline silicon and the metal layer, unlike the coating of the silicon base material with the film of the conductive material, heat generation of the discharge electrode, Even if cooling is repeated, the conductive layer 12 of the discharge electrode does not crack or peel due to thermal stress. Also, it is possible to prevent cracking due to external impact.

Since the conductive layer 12 is formed on the base end face of the discharge electrode 10 as well, it can be used for an ionizer of the type in which the base end face of the discharge electrode 10 also comes into contact with a contact for high voltage application. You can

Next, a method of manufacturing a discharge electrode for an ionizer will be described. The tip 11b of the rod 11 is masked in advance. Next, a metal such as gold or aluminum is vapor-deposited on the entire surface of the rod 11 by vacuum vapor deposition. Next, the rod 11 is heated in a high temperature furnace. When the metal is gold, the heating temperature is about 1000 degrees. As a result, the polycrystalline silicon base material located on the surface layer of the rod 11 reacts with the metal to form the inner peripheral portion of the conductive layer 12. The outer metal serves as a metal layer as an outer peripheral portion of the conductive layer 12. It is not necessary to remove excess metal on the surface of the bar 11 by etching to form the metal layer. Next, the masking is removed to expose the polycrystalline silicon base material of the tip portion 11b.

As another manufacturing method, as shown in FIG. 3, a cylindrical rod member 20 made of high-purity polycrystalline silicon is used.
A metal such as gold or aluminum is vapor-deposited on all surfaces of the metal by vacuum vapor deposition. Next, the metal is reacted with the polycrystalline silicon base material by heating to form the conductive layer 12. Next, the tip is ground into a conical shape to obtain the discharge electrode 10 having the tip 11b in which the polycrystalline silicon base material is exposed, as in FIG.

Further, as in the embodiment of FIG. 4, the conductive layer 12 may be formed by simply adhering a metal such as gold or aluminum to the base end surface and the outer peripheral surface of the rod 11 made of a polycrystalline silicon base material. Good. In this example, there is almost no reaction between the metal and the silicon material. The discharge electrode 10 is manufactured as shown in FIG. In FIG. 5, reference numeral 30 denotes a heating table that is heated by the heater 31, and the heating table 30 is made of a material having a thermal expansion coefficient smaller than that of the metal used as the material of the conductive layer 12. On the upper surface of the heating table 30, an elongated recess 30
a is formed, and the recess 30a has a smooth inner peripheral surface and a bottom surface. The metal is accommodated in the recess 30a and melted, and then the bar 11 is inserted into the recess 30a. Next, with the rod 11 inserted, the heating table 30 is cooled,
Solidify the conductive material. As a result, the discharge electrode 1 of FIG.
0 is obtained. When the contact is a cylinder having a screw on the inner peripheral surface, a screw 12a is formed on the outer periphery of the metal conductive layer 12 of the discharge electrode 10, as shown in FIG. In this case, the metal conductive layer 12 preferably has a thickness of about 2 mm.

The present invention is not limited to the above embodiment and various modes can be adopted. The conductive material may be attached to the rod material by a vacuum plating method such as cathode sputtering instead of the vacuum deposition. Further, the shape of the tip of the discharge electrode can be various shapes such as a triangular pyramid shape and a quadrangular pyramid shape.
Further, the conductive layer 12 may be formed not only on the entire outer peripheral surface of the columnar base portion 11a but only on the outer periphery of the portion contacted by the contactor. A conductive layer may be formed by diffusing phosphorus or boron around the outer circumference of a rod made of a polycrystalline base material.

[0017]

According to the discharge electrode of the present invention, since the conductive layer having a lower electric resistance than that of the polycrystalline silicon base material is formed on the outer periphery of the contact portion of the contact, damage to the discharge electrode due to high voltage can be prevented. . Further, since polycrystalline silicon is used, corona discharge at the tip portion is possible without adding impurities unlike single crystal silicon. Since only silicon is scattered by the corona discharge at the tip portion, it does not adversely affect the semiconductor manufacturing. Further, in the discharge electrode according to the second aspect, since the conductive layer is formed by the reaction layer of metal and polycrystalline silicon, cracking or peeling due to thermal stress of the conductive layer does not occur. In the discharge electrode according to the third aspect, since the conductive layer is composed of the metal layer, it is possible to prevent cracks from being generated when a mechanical shock is applied from the outside.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an ionizer including a discharge electrode according to the present invention.

FIG. 2 is a side view of a discharge electrode for an ionizer.

FIG. 3 is a side view of a bar as an electrode material.

FIG. 4 is a cross-sectional view of a discharge electrode for an ionizer according to another aspect.

FIG. 5 is a cross-sectional view showing the method of manufacturing the discharge electrode of FIG.

FIG. 6 is a cross-sectional view of a discharge electrode for an ionizer according to still another aspect.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ionizer 10 Discharge electrode 11 Bar material 11a Base part 11a 'Contact part 11b Tip part 12 Conductive layer 20 Bar material

Claims (3)

[Claims] 1. A bar material comprising polycrystalline silicon as a base material, wherein a conductive layer having a lower electric resistance than that of the polycrystalline silicon base material is provided on an outer peripheral surface of a portion of the bar material which receives a high voltage from a contact of an ionizer. A discharge electrode for an ionizer, characterized in that the polycrystalline silicon base material is exposed at the tip of the bar material. 2. The conductive layer is composed of a reaction layer of a metal and a polycrystalline silicon base material.
Discharge electrode for the ionizer described. 3. The discharge electrode for an ionizer according to claim 1, wherein the conductive layer is composed of a metal layer attached to the outer peripheral surface of the rod member.