JPH0451447A - Ion implantation device and its method of use - Google Patents

Abstract

PURPOSE:To nullify noises generated from power supplies substantially by using a battery to each power supply for a neutralizing means, and thereby eliminating rotund-in of noises from an AC line. CONSTITUTION:A filament 8 is installed on the side of a Faraday case 4 in order to prevent electric discharge or the like because of positive charging on the surface of a base board 5 associate with irradiation with an ion beam 2, and the primary electrons 11 emitted therefrom are allowed to bombard the inner wall of the Faraday case 4. Thereby secondary system 12 is emitted, and the positive electric charges with the ion beam 2 are neutralized. Batteries 14a, 16a, 18a, 20a are used to a filament power supply 14, emission power supply 16, holder bias power supply 18, and Faraday bias power supply 20, respectively, which supply power to a neutralizing means for the described purpose. From the battery 14a, power is supplied to the filament 8 via a filament current control circuit 28, which controls the filament current under control by a neutralization control circuit 24. Because these control circuits 28, 24 lead directly to the Faraday system, batteries 28a, 24a are used also to these power supplies.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention provides an ion implantation apparatus and a neutralization means that supplies electrons to a substrate into which ions are to be implanted to prevent the substrate from being charged due to ion implantation. Regarding its usage.

[Conventional technology]

An example of this type of ion implantation device will be shown in Part 3.

This device basically consists of a substrate 5 held in a holder 6.
The structure is such that the ion beam 2 is irradiated onto the ion beam 2 to perform ion implantation. The substrate 5 is, for example, an insulating substrate such as a glass substrate or a semiconductor substrate, but is not limited to a specific one.

In addition, by housing the holder 6 in the Faraday case 4 and arranging a negative potential pressor electrode 3 in its artificial part, secondary radiation emitted when the ion beam 2 hits the holder 6 etc. By preventing electrons from escaping to the ground, the beam current measuring device 26 can accurately measure the beam current rb of the ion beam 2.

Further, as the ion beam 2 is irradiated, the surface of the substrate 5 is
Particularly when the surface is an insulator, the following neutralization means is provided to prevent problems such as discharge due to positive charging. That is, a filament 8 is provided on the side of the Faraday case 4, and the primary electrons 11 emitted from the filament are applied to the inner wall of the Faraday case 4 in this example to emit secondary electrons 12 from there, and the secondary electrons 12 are transferred to the substrate. 5 to neutralize the positive charge caused by Ionbee J,2. 14 is filament l~power supply for heating filament 1-8, 16 is filament l~
This is an emission power source for extracting primary electrons 11 from 8. Further, 18 is a Boulder bias power supply for efficiently guiding the secondary electrons 12 to the substrate 5 on the holder 6, and 20 is a Faraday bias power supply for preventing the secondary electrons 12 from escaping from the Faraday case 4, but these are omitted. In some cases, it may be done.

During ion implantation, a resistor 22 inserted in series with the holder bias power supply 18 has a beam current 1 generated by the ion beam 2.
A holder current Ih (-1b-L), which is a composite of the
The primary electrons 1 are emitted from the filament 8 by controlling the filament power supply 14 to control the filament current.
1, thereby setting the holder current rh to a desired constant value (which, empirically speaking, is not 0 but, for example, −10
(preferably about 0 μA), so that the substrate 5 can be effectively prevented from being charged.

[Problem to be solved by the invention]

Conventionally, the control power supplies for the filament power supply 14, the emission power supply 16, the holder bias power supply 18, the Faraday bias power supply 20, the neutralization control circuit 24, etc. for the neutralization means are all rectified alternating current to produce direct current. However, countermeasures against noise from these power supplies have become an important issue.

This is because these power supplies are directly connected to the beam current measurement system by the beam current measuring device 26, and the beam current 1b is very small (for example, about several tens of μA to several mA).
As a result, these power supplies become a noise source, which interferes with beam current measurement.

Conventionally, as a countermeasure to this, noise cut transformers that remove external noise have been used in each of the above power supplies, but even with the use of such noise cut transformers, it is currently not possible to achieve sufficient noise reduction. It is. Simply put, this is because noise inevitably circulates from the AC line through noise forces and stray capacitance that exists between the windings of the transformer or between the windings and the core.

Therefore, the main object of the present invention is to provide an ion implantation device and a method of using the same that can almost completely eliminate noise generated from each power source for the neutralization means as described above.

[Means to solve the problem]

In order to achieve the above object, the ion implantation apparatus of the present invention provides a filament power supply for heating the filament, an emission power supply for extracting primary electrons from the filament, and a measurement circuit and a control circuit directly connected to the Faraday system. It is characterized by using a battery for each control power source.

In that case, two systems of batteries for the filament power source, a charging circuit common to both, and a switching means for alternately connecting one of the two batteries to the filament side and the other to the charging circuit side. may also be provided.

Further, in the method of using the ion implantation apparatus according to the present invention, two systems of batteries are provided for the filament power source, and when one is used as a power supply source for the filament 1-, the other is charged. Both batteries are switched at predetermined time intervals, and the emission power source battery and the control power source battery are charged when the filament is not in use.

[Effect]

By using a battery for each power source as described above, noise from the AC line can be eliminated. As a result, noise generated from each power source can be almost completely eliminated.

In that case, the filament consumes the most power, so
By providing two systems of batteries for the filament power source and switching between them as described above, the neutralization means can be used continuously for a long time even though batteries are used.

Similarly, according to the method of use as described above, the neutralization means can be used continuously for a long time even though a battery is used.

〔Example〕

FIG. 1 is a circuit diagram showing a power source for a neutralization means in an ion implantation apparatus according to an embodiment of the present invention. For the configuration of the ion implantation device, refer to FIG. 3, and illustration and description thereof will be omitted here.

In this embodiment, a battery 14. a, emission power supply 1
Insert battery 1.6a into 6, holder bias voltage #1
8, battery 18a, Faraday bias power supply 20
A battery 20a is used in each case.

Electric power is supplied to the filament 8 from the battery 14a via a filament current control circuit 28 in this example. The filament current control circuit 28 includes an I-transistor 28b that prevents excessive current input to the filament 8 and stabilizes the filament current, and a shunt resistor 28c for detecting the filament current.
The filament current is controlled under the control of the neutralization control circuit 24 described above.

Since the filament current control circuit 28 and the neutralization control circuit 24 are directly connected to the Faraday system (that is, the Faraday case 4, holder 6, etc. connected to the heem current measuring device 26), these control power supplies are also connected. , batteries 28a and 24a are used, respectively. Also,
An insulated amplifier circuit (not shown) is also connected to an emission current detection resistor 30, which will be described later, but since it has the same potential as the filament current control circuit 28, it is also used as the battery 28a.

The battery 16a for the emission power source is not particularly controlled in this example. However, a resistor 30 is inserted in series with it to serve both as detection of the emission current and as current limiting when the load shifts. This statement also applies to the battery 18a for holder bias power supply and the battery 20a for Faraday bias power supply. 22 and 32 are resistors that serve both for current detection and current limiting, respectively.

By using a battery for each power source as described above, unlike the conventional power source that rectifies AC through a noise cutter lance, it is possible to eliminate noise from entering the AC line. .

Therefore, noise generated from each power source can be almost completely eliminated, and even if the beam current is minute, it will not interfere with its measurement.

By the way, in order to use the neutralization means continuously for a long time, each battery must be charged appropriately in consideration of its load. An example of a preferable means for this purpose will be explained with reference to FIG.

An ion implanter like the one discussed here is not operated (ion implanted) continuously for three days while fishing on a boat. Therefore, it is sufficient that the above-mentioned neutralization means can be used continuously for about three days, but since the filament 8 consumes the largest amount of power, the battery 14a for it is particularly problematic. Batteries for other power sources, i.e. Hashitery-16a for emission, battery 1 for holder bias
8a, since the control batteries 24a and 28a have a small load, they can normally be used continuously for 5 to 6 days or more with a single charge. Further, the battery 20a for Faraday bias has a beam current T of the ion beam 2.
Since it is charged by b, no special charging is required.

Therefore, in the example shown in FIG. 2, to put it simply, two systems of batteries 14a, 14a2 are provided for the filament power source, and these are used while being charged alternately.
a, 18a, 24a, and 28a are charged when the filament 8 is not in use (that is, when the neutralization means is not in use).

In detail, the two systems of batteries 14a and 14
a2, selector switch (e.g. magnetic switch) 3
6, one of them is alternately connected to the filament 8 side and the other to the charging circuit 34 side, and when one is used as a power supply source to the filament 8, the other is charged by the charging circuit 34. ing. This switching is performed, for example, every 10 to 20 minutes while the neutralization means is in use (however, it is not switched during ion implantation), and every 30 minutes when the neutralization means is not in use.

This setting may be performed using a timer, for example.

In that case, during the switching operation of the selector switch 36 (for example, 50
mS), the filament current will be interrupted momentarily, but if this is left unattended, the current control circuit 2 will flow to the filament 1.
Since this will have an adverse effect on the 1-range metal 28b, etc. in the 8, the third battery 14 is connected to the filament circuit as in this example.
It is preferable to keep a3 connected at all times. In this way, the filament current will continue to flow even when the batteries 14a and 14a2 are switched.

At this time, the battery 14a3 becomes the battery 14a+
Furthermore, when directly connected to the battery 14a2, since the internal resistance of the battery is very small, a large current will flow into the battery 14a3 due to the voltage difference between the two batteries. In order to prevent this, it is preferable to do the following. That is, in this example, the batteries are connected to each other via the resistor 38, and the battery 14a3 is charged via this. However, since this resistor 38 alone limits the current when power is supplied from the battery 14a3 to the filament l-8, a diode 40 is connected to the resistor 38.
are connected in parallel, and the battery 14a.

When power is supplied from the filament 8 to the filament 8, a current is made to flow through this diode 40.

On the other hand, for the emission power source 16a, a charging circuit 42 and a changeover switch (for example, a relay) 44
A selector switch 44 is provided to charge the battery when the neutralization means is not in use. The battery 18a for the holder bias power source is also provided with a charging circuit 46 and a changeover switch (for example, a relay) 48, and the changeover switch 48 is switched to charge the battery 18a when the neutralization means is not in use. Furthermore, although not shown, the control batteries 24a and 28a are also charged by a charging circuit when the neutralization means is not in use, similarly to the batteries described above.

Further, due to the circuit configuration, the Faraday bias battery 20a continues to be charged by the beam current Ib of the ion beam 2 flowing into it, as described above.

Therefore, as in this embodiment, the battery 20 has a resistor 50 and a Zener diode 52 connected in series.
It is preferable to connect the battery 20a in parallel with the battery 20a and discharge the battery 20a through this circuit when the voltage of the battery 20a reaches a certain voltage (the Zener voltage of the Zener diode 52).

By doing as described above, it becomes possible to use the neutralization means continuously for a long time (for example, about 3 days) even though a battery is used.

Note that, as described above, the holder bias power supply and the Faraday bias power supply may be omitted, and in that case, the batteries 18a, 20a and their associated circuits are also omitted.

(Effects of the Invention) As described above, according to the ion implantation apparatus according to the present invention,
Since a battery is used for each power source for the neutralization means, noise from the AC line can be eliminated, and as a result, noise generated from each power source can be almost completely eliminated.

Therefore, even if the beam current is minute, it will not interfere with its measurement.

In addition, by providing two battery systems for the filament power source, a charging circuit common to both, and a battery switching means, it is possible to use the neutralization means continuously for a long time even though batteries are used. become.

Similarly, according to the method of using the ion implantation device according to the present invention, the neutralization means can be used continuously for a long time even though a battery is used.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a power source for a neutralization means in an ion implantation apparatus according to an embodiment of the present invention. FIG. 2 is a circuit diagram showing a power source for a neutralization means in an ion implantation apparatus according to another embodiment of the present invention. FIG. 3 is a diagram partially showing an example of an ion implantation apparatus including a neutralization means.

Claims (3)

[Claims] (1) Ion implantation in which the primary electrons emitted from the filament are applied to a Faraday-based structure to emit secondary electrons, and these secondary electrons are supplied to the substrate on the holder into which the ions are to be implanted. The apparatus is characterized in that batteries are used as a filament power source for heating the filament, an emission power source for extracting primary electrons from the filament, and a control power source for a measurement circuit and a control circuit directly connected to the Faraday system. Ion implantation equipment. (2) Two battery systems for the filament power source, a charging circuit common to both, and a switching means for alternately connecting one of the two battery systems to the filament side and the other to the charging circuit side. The ion implantation apparatus according to claim 1, comprising: (3) Ion implantation in which the primary electrons emitted from the filament are applied to a Faraday structure to emit secondary electrons, and these secondary electrons are supplied to the substrate on the holder into which the ions are to be implanted. Use of a device in which a battery is used as a filament power source for heating the filament, an emission power source for extracting primary electrons from the filament, and a control power source for a measurement circuit and a control circuit directly connected to the Faraday system. In the method, two batteries are provided for the filament power source, and when one is used as a power supply source for the filament, the other is charged and both batteries are switched at predetermined intervals, and A method of using an ion implanter, characterized in that the emission power source battery and the control power source battery are charged when the filament is not in use.