KR20070074199A - Plasma flood gun of an ion implanter - Google Patents

Abstract

A plasma flood gun of an ion implanter is provided to prevent short circuit thereof by reducing the amount of contaminants such as introduced gas, ionized gas, and electrons to be attached on a surface of an insulating member. A filament(152) is installed at a chamber for defining a traveling path of an ion beam in an ion implantation process. An insulating member(154) is arranged between the filament and the chamber in order to maintain an insulating state between the filament and the chamber. A fixing member(158) is extended through the filament, the insulating member, and the chamber in order to fix the filament to the chamber. A washer(156) is arranged between the insulating member and the filament. The washer includes a disk having a center hole and a cover ring for covering the insulating member.

Description

Plasma flood gun of an ion implanter

1 is a schematic cross-sectional view for explaining a plasma flood gun of a conventional ion implantation device.

2 is a schematic cross-sectional view for describing an ion implantation apparatus according to an embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view for explaining the plasma flood gun shown in FIG. 2.

4 is a schematic exploded perspective view illustrating the washer shown in FIG. 3.

Explanation of symbols on the main parts of the drawings

100 ion implantation device 110 ion source

112: arc chamber 120: transmission unit

130: beam line chamber 140: end station chamber

142 ion implantation chamber 148 Faraday cup assembly

150: plasma flood gun 152: filament

154: insulating member 156: washer

158: fixing member

The present invention relates to a plasma flood gun of an ion implantation apparatus, and more particularly, to a plasma flood gun of an ion implantation apparatus for preventing the charge up of the semiconductor substrate by the ion beam generated in the ion implantation apparatus will be.

In recent years, with the rapid spread of information media such as computers, semiconductor devices have also been developed rapidly. In terms of its function, the semiconductor device is required to operate at a high speed and to have a large storage capacity. In response to these demands, semiconductor technologies have been continuously developed in the direction of improving integration, reliability, and response speed.

In general, semiconductor devices are manufactured by sequentially, selectively and repeatedly performing unit processes such as deposition, photolithography, etching, ion implantation, polishing, cleaning, and drying on a semiconductor substrate.

Among the unit processes, an ion implantation process is a process of implanting the ions by irradiating an ion beam made of desired ions to a specific region of the semiconductor substrate, compared to the thermal diffusion technology, the number and implantation depth of ions implanted in the specific region There is an advantage that can be adjusted.

An ion implantation apparatus for performing the ion implantation method accelerates ionized impurities using high energy to inject an ion beam onto a surface of a semiconductor substrate.

The ion implantation apparatus is largely composed of an ion source, a beam line chamber, and an end station chamber. The ion source ionizes the source gas using the emission of electrons, the beam line chamber directs ions provided from the ion source to an end station chamber, and at least one semiconductor substrate is disposed in the end station chamber.

If ions emitted from the ion source are injected into the substrate with a positive charge polarity, the substrate is stored with a positive charge polarity, which acts as a repulsive force for the ion beam continuously injected, resulting in process failure. To prevent this problem, the end station is equipped with a plasma flood gun to prevent unnecessary power storage on the substrate.

The plasma flood gun is installed on a path of an ion beam used in an ion implantation process onto a semiconductor substrate, and emits electrons toward the ion beam. The electrons neutralize the ion beam having a positive polarity, thereby preventing the ion storage phenomenon generated during the injection of the ion beam onto the substrate.

Specifically, the plasma flood gun supplies a gas for plasma generation to its own reaction chamber provided in the end station, and a filament power source is connected to the filament installed in the reaction chamber. The plasma generated by the plasma flood gun emits electrons toward the ion beam before the ion beam traveling horizontally reaches the vertically standing substrate. The ion beam is neutralized by the electrons, thereby preventing the charge-up phenomenon of the semiconductor substrate.

1 is a cross-sectional view schematically showing a plasma flood gun of a conventional ion implantation device.

Referring to FIG. 1, the conventional plasma flood gun 10 shown includes a filament 12, an insulating member 14, and a fixing member 16.

The filament 12 emits electrons to neutralize the ion beam, and the insulating member 14 maintains insulation between the filament 12 and a chamber (not shown). It is arranged between the chambers.

The fixing member 16 extends through the filament 12, the insulating member 14, and the chamber, and fixes the filament 12 to the chamber, the insulating member 14 and the filament 12. In order to distribute the load which the holding member 16 receives, the washer 18 is provided.

The gas, ionized gas, and electrons introduced during the ionization process are mixed in the chamber of the ion implantation device, and a part thereof is stacked on the surface of the insulating member 14 of the plasma plug gun 10, such as a conductive layer. To form contaminants; The conductive layer formed on the insulating member 14 generates electrical problems such as short-circuit of the power supply even though the thickness thereof is thin, and these problems serve as a main factor to destabilize the ionization process. That is, the contaminants cause leakage of current flowing to the filament 12, and the insulation function of the insulating member 14 is lost. As a result, the ion implantation process not only becomes unstable, but also shortens the service life of the plasma flood gun.

An object of the present invention for solving the above problems is to provide a plasma flood gun of the ion implantation device to minimize the contamination of the insulating member, to extend the service life of the plasma flood gun.

In order to achieve the object of the present invention, the present invention, the filament and the filament is mounted in a chamber defining a path of the ion beam used in the ion implantation process for the semiconductor substrate, and emits electrons to neutralize the ion beam An insulating member disposed between the filament and the chamber, the fixing member and the insulating member extending through the filament, the insulating member, and the chamber to fix the filament to the chamber to maintain the insulation between the chambers; A washer disposed between the filaments and including a disk having a central hole through which the fixing member passes and a covering ring surrounding the insulating member to prevent the insulating member from being damaged by the ions of the ion beam. It includes.

The chamber is formed with a hole through which the fixing member passes, the insulating member includes a body to be fitted to the hole and a head for maintaining a predetermined distance between the filament and the chamber, the cover ring It is arranged to surround the head. At this time, the washer is made of molybdenum (molybdenum) material.

The plasma flood gun of the ion implantation apparatus according to the present invention configured as described above prevents the formation of a foreign material layer on the insulating member during the injection of the ion beam into the substrate. Therefore, the lifetime of the plasma flood gun is extended, and the maintenance period of the ion implantation apparatus is lengthened to improve the productivity.

Hereinafter, a plasma flood gun of an ion implantation apparatus according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a schematic cross-sectional view illustrating an ion implantation apparatus according to an embodiment of the present invention, FIG. 3 is a schematic cross-sectional view illustrating the plasma flood gun shown in FIG. 2, and FIG. 4 is shown in FIG. 3. Is a schematic exploded perspective view for explaining the washer.

2 to 4, the illustrated ion implantation apparatus 100 includes an ion source 110 and a predetermined portion of a semiconductor substrate (not shown), such as a silicon substrate, with the ions provided from the ion source 110. An end station chamber (140) for handling the substrate for implantation into the end station chamber (140), the ion source (110) and the end station chamber (140), and the ions from the ion source (110) to the end station chamber ( And a transmitting unit 120 for transmitting to 140.

The ion source 110 includes an arc chamber 112 capable of generating ions and a filament (not shown) of the arc chamber 112 for emitting electrons electronically into the arc chamber 112. A filament current for emitting electrons is applied to the filament of the arc chamber 112, and an arc voltage biased with respect to the filament current is applied to the arc chamber 112. That is, the filament of the arc chamber 112 is used as a cathode (cathode) and the arc chamber 112 is used as an anode (anode).

The source gas supplied to the arc chamber 112 may be ionized by the collision with the electrons. In addition, an ion source 110 such as a radio frequency type duoplasmatron, a cold cathode type, a sputter type, or a penning ionization type may be used.

The transmission unit 120 includes an extraction electrode 122, a mass analyzer 124, a quadrupole lens 126, an accelerator 128, a beam line chamber 130, and the like, disposed along a path of an ion beam. The extraction electrode 122 extracts ions formed in the arc chamber 112 and forms an ion beam, and the ion beam formed through the extraction electrode 122 is guided to the mass analyzer 124. The mass spectrometer 124 selects specific ions for implantation into the semiconductor substrate among the ions constituting the ion beam. An ion beam composed of ions selected by the mass spectrometer 124 is focused by the quadrupole lens 126 and accelerated by the accelerator 128 to have the desired energy.

The accelerated ion beam is directed to a semiconductor substrate located in the end station chamber 140. The end station chamber 140 includes an ion implantation chamber 142 in which at least one semiconductor substrate is located, a substrate support 144 for supporting the semiconductor substrates in the ion implantation chamber 142, and the support. A plasma flood gun provided with a motor 146a for rotating the 144, a linear motor 146b for linearly moving the support 144, and an ion beam used for an ion implantation process of the substrate. 150, a Faraday cup assembly 148, etc. for measuring the ion current of the ion beam.

The substrate support 144 has a disk shape, and a plurality of semiconductor substrates 10 are disposed along an edge. A plurality of chucks (not shown) for supporting the semiconductor substrate and openings 142a for passing the ion beam are provided on the substrate support 144.

The motor 146a is connected to the rear surface of the support 144, rotates the support 144, and the linear motor 146b linearly moves the support 144. During the ion implantation process, the support 144 may be rotated and vertically moved by the motor 146a and the linear motor 146b so that the ion beam is entirely implanted into the semiconductor substrates.

The plasma flood gun 150 is provided to prevent a charge up phenomenon caused by accumulation of positive charges on a substrate. The plasma flood gun 150 is installed on a path through which ion beams used in an ion implantation process are directed toward a substrate, and includes a filament 152, an insulating member 154, a washer 156, and a fixing member 158. Consists of

The plasma flood gun 150 neutralizes an ion beam having positive charges injected into the substrate by the emission of electrons from the filament 152.

The filament 152 is in the shape of a “U” shape and is installed through one side of the insulating member 154, which is described later, at both ends thereof, thereby stably fixing and electrically connecting the filament 152. In one embodiment of the present invention, the filament 152 generally has a "U" shape, but may alternatively have a spiral structure to increase the length in unit volume. The filament having the helical structure as described above has a long length and thus can emit a large amount of electrons. As a result, since the amount of electrons colliding with the gas atoms supplied in the chamber is high, it is possible to increase the ionization efficiency that can ionize the gases. Both ends of the filament 152 are connected to the filament power supply device 152a, and receive power from the power supply device 152a to emit electrons.

The insulating member 154 is disposed between the filament 152 and the self reaction chamber 160 to maintain insulation between the filament 152 and the self reaction chamber 160. Two holes are formed in the sidewall of the self-reaction chamber 160 to insert and fix the insulating member 154. The insulating member 154 is composed of a body forcibly fitted into a hole formed in the self-reaction chamber 160 and a head for maintaining a predetermined distance between the filament and the chamber. The filament 152 is more firmly fixed in position by the insulating member 154, and the filament 152 and the self-reaction chamber 160 should not contact each other to maintain insulation when the position is fixed.

The fixing member 158 may be a pin or bolt. The fixing member 158 extends through the filament 152, the insulating member 154, and the self reaction chamber 160, and fixes the filament 152 to the self reaction chamber 160. In addition, in order to accommodate the fixing member 158, a hole 158 through which the fixing member passes is formed in the self-reaction chamber 160.

A washer 156 is interposed between the insulating member 154 and the filament 152. The washer 156 is composed of a disk 156a and a covering 156b.

The disk 156a has a central hole through which the fixing member 158 passes, and by widely distributing the load received by the head portion of the fixing member 158, the disk 156a of the fixing member 158 and the filament 152 To prevent possible damage to the contact surface.

The covering 156b surrounds the insulating member 154 to prevent the insulating member 154 from being damaged by the ions of the ion beam. The covering 156b is hollow and has an opening formed at one side thereof, and is disposed to surround the head. The washer 156 is made of molybdenum material having excellent corrosion resistance and heat resistance.

A reflector (not shown) may be further provided in the end station unit 140 in which the plasma flood gun 150 is installed. The reflector may further increase the neutralization efficiency of the ion beam by colliding electrons generated in the ion implantation apparatus 100 by the plasma flood gun 150 to generate high energy secondary electrons. The path is converted by the ion beam to neutralize the positive charge accumulated on the substrate. In addition, the plasma flood gun 150 emits electrons by colliding with a reaction gas supplied from the gas supply unit 162 into the reaction chamber 160.

Looking at the coupling of the plasma flood gun 150, two holes for the fixing member 158 is formed in the self-reaction chamber 160. The fixing member 158 penetrates the filament 152 and then sequentially passes through the washer 156 and the insulating member 154 to be finally coupled to the self-reaction chamber 160. The filament 152 and the self-reaction chamber 160 are fixed to the fixing member 158 by a predetermined interval without being in contact with each other by the insulating member 154.

The plasma flood gun 150 configured as described above does not expose the insulating member 154 to an external environment in which ionized gas is scattered, thereby preventing contamination of the insulating member 154.

That is, since the insulating member 154 is blocked from the external environment by the washer 156, the gas, ionized gas, and electrons introduced during the ionization process are introduced into the ion implantation device 142. Adsorption on the surface of 154 may be minimized.

The plasma flood gun configured as described above has the following effects.

An ion beam is generated from the ion source to perform the ion implantation process. A filament current for emitting electrons is applied to the filament in the arc chamber, and an arc voltage biased with respect to the filament current is applied to the arc chamber.

The ion beam generated from the ion source is converted by the transmission unit into the traveling path of the ion beam and accelerated to have the desired energy.

The accelerated ion beam is directed to a semiconductor substrate located in the end station unit. At this time, the ion beam is neutralized by the plasma flood gun and injected into the substrate.

Specifically, in the plasma flood gun, xenon gas is supplied through a gas supply unit, and a high voltage is applied to a filament power supply device connected to both ends of the filament. At this time, the filament for electron emission in the plasma state is introduced into the reaction chamber of the end station unit formed in a vacuum state. The filament, which receives a constant power from the power supply, emits a lot of electrons. The electrons are discharged through the discharge holes in the reaction chamber and scattered on the path of the ion beam for ion implantation process to the substrate.

Accordingly, the outermost electrons of xenon and electrons emitted from the filament are replaced inside the end station unit, and the electrons separated from the xenon are recombined with the positive charge to be injected onto the substrate. The ion beam supplied from the ion source is neutralized and injected into a vertically standing substrate.

According to the present invention as described above, it is possible to prevent the short circuit of the plasma flood gun by minimizing the adsorption of contaminants such as gas, ionized gas, and electrons in the ionization process on the surface of the insulating member inside the ion implantation device. have.

As a result, by preventing malfunction of the ion implantation apparatus and component loss, the defective rate of the ion implantation process is reduced, and the ion implantation process can be performed very stably.

While the foregoing has been described with reference to preferred embodiments of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. It will be appreciated.

Claims (4)

A filament mounted in a chamber defining a traveling path of an ion beam used in an ion implantation process onto a semiconductor substrate, the filament emitting electrons to neutralize the ion beam; An insulation member disposed between the filament and the chamber to maintain insulation between the filament and the chamber; A fixing member extending through the filament, the insulating member and the chamber and for fixing the filament to the chamber; And A cover ring disposed between the insulating member and the filament and covering the insulating member to prevent the insulating member from being damaged by the ions of the ion beam and a disk having a central hole through which the fixing member passes. Plasma flood gun of the ion implantation apparatus comprising a washer comprising a. The chamber of claim 1, wherein a hole through which the fixing member passes is formed in the chamber, and the insulating member includes a body that is tightly coupled to the hole, and a head for maintaining a predetermined distance between the filament and the chamber. Plasma flood gun of the ion implantation apparatus, characterized in that. 3. The plasma flood gun of an ion implantation device as recited in claim 2, wherein said cover ring is disposed to surround said head. The plasma flood gun of an ion implantation apparatus according to claim 1, wherein the washer is made of molybdenum.

Images