JPH0722039Y2 - Scanning power supply with abnormality detection circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a scanning power supply used for electrostatically scanning an ion beam in an ion implantation apparatus, for example, with an abnormality detection circuit.

[Conventional technology]

 FIG. 2 shows a conventional example of this type of scanning power source.

This scanning power supply has a voltage amplifier circuit 6, and includes a scanning signal S _i including a triangular wave component (usually a triangular wave signal superimposed on a DC offset signal) provided from a signal source 2,
The feedback signal S _o returned from the output part of the voltage amplification circuit 6 to the input side via the feedback CR circuit 8 (but not limited to the configuration shown in the figure) is matched at the matching point (summing point) P and both are compared. Difference of (S _i −S _o )
Is taken (there is actually an opposite phase, so there is a difference if they match each other), and in this example, it is amplified by the differential amplification amplifier 4 and supplied to the voltage amplification circuit 6, whereby the voltage amplification circuit 6 Control the desired high scanning voltage from there
I am trying to output VS.

The scanning voltage VS is applied to a scanning electrode (not shown) in, for example, an ion implantation device and used to scan the ion beam or the like in the horizontal direction or the vertical direction.

By the way, taking an ion implantation apparatus as an example, the apparatus is used in a semiconductor factory, and the factory is normally operating for 24 hours, and troubles with the apparatus reduce the production capacity of the factory itself. Further, since many power supplies are mounted on the ion implantation apparatus, and the outputs of the power supplies affect each other, it is difficult to find out when the power supplies have failed.

In particular, since the failure of the scanning power source is difficult to understand (for example, it can be judged only by an external event that occurs as a result of poor injection uniformity with respect to the target), an abnormality detection circuit may be attached to it as in this example. .

That is, the feedback signal S _o ′ is taken out from the output part of the voltage amplification circuit 6 via the CR circuit 8 ′ similar to the feedback control CR circuit 8 described above, while the scanning signal S _i from the signal source 2 is amplified by the amplifier 10. Waveform adjustment and gain adjustment, etc. are carried out through the respective signals and 14, and the feedback signal S _o ′
And an somewhat smaller upper limit signal S _i ′ and a somewhat smaller lower limit signal S _i ″, which are compared with the feedback signal S _o ′ in comparators 18 and 20, respectively, and OR When the feedback signal S _o ′ is greater than the upper limit signal S _i ′ or less than the lower limit signal S _i ″ in the circuit 22, the output of the OR circuit is ORed.
An abnormality signal SA is output from 22 to detect an abnormality in the scanning power supply.

[Problems to be solved by the device]

However, in the conventional scanning power supply with abnormality detection circuit as described above, if the waveforms of the upper limit signal S _i ′ and the lower limit signal S _i ″ differ from the waveform of the feedback signal S _o ′, abnormality detection cannot be performed correctly, The amplifiers 10 and 14 are provided with complicated CR circuits 12 and 16 for feedback (but not limited to the configuration shown in the drawing), and the trimmer capacitors 12a and 16a and the volumes 12b and 16b included therein are finely adjusted to form a waveform. It requires precise adjustment, and this adjustment work is very time-consuming, and it is difficult to set the abnormality detection range because it is related to the waveform. There is also the problem of getting stuck.

Therefore, the present invention mainly provides a scanning power supply with an abnormality detection circuit that does not require adjustment work for the abnormality detection circuit, can easily set an abnormality detection range, and can reduce the number of parts. To aim.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the scanning power supply with an abnormality detection circuit of the present invention uses a difference between the scanning signal and the feedback signal, which is generated in the feedback loop of the voltage amplification circuit as described above, in the comparison circuit to a predetermined upper limit value and The comparison is made with a lower limit value, and when the difference is out of the range of the upper limit value and the lower limit value, an abnormal signal is output from the comparison circuit.

[Operation] The above difference is a small value in the normal state, but if any abnormality occurs in the scanning power source, the value becomes extremely large. Therefore, the difference in the scanning power supply can be detected by comparing this difference with the predetermined upper limit value and the lower limit value in the comparison circuit.

Further, in this case, the upper limit value and the lower limit value may be a mere DC voltage, and it is not necessary to bother to create a signal similar to the output feedback signal for abnormality detection as in the conventional example. .

〔Example〕

FIG. 1 is a circuit diagram showing a scanning power supply with an abnormality detecting circuit according to an embodiment of the present invention. The same or corresponding parts as those in the example of FIG. 2 are designated by the same reference numerals, and the differences from the conventional example will be mainly described below.

In this embodiment, the abutting point P as described above is used.
In order to take out the difference (S _i −S _o ) between the scanning signal S _i and the feedback signal S _o , which is created in step S3, without affecting the preceding and following circuits, between the matching point P and the differential amplification amplifier 4. For example, a buffer amplifier 30 with an amplification of 1 is inserted,
The difference (S _i −S _o ) is taken out from the output section, is input to the find comparator 32, and is compared with a predetermined upper limit value S _H and lower limit value S _L, and the difference (S _i −S _o). ) Is out of the range of the upper limit value S _H and the lower limit value S _L , the abnormal signal SA is then output.

The difference (S _i −S _o ) is very small in a normal state (for example, about ± several mV to ± several tens of mV), but if some abnormality occurs in the scanning power supply, the value becomes extremely larger than the above value. growing.

Therefore, this difference (S _i −S _o ) is calculated by the window comparator 32.
At a predetermined upper limit S _H (eg ± 5 V) and lower limit S _L
By comparing with (for example, −5V), the abnormality of the scanning power supply can be detected.

Moreover, in this way, the upper limit value S _H and the lower limit value S _L
May be a mere DC voltage, and a signal S _i ′ similar to the output feedback signal S _o ′ for abnormality detection as in the conventional example.
And you don't have to do the hassle of making S _i ″.

As a result, the work such as the waveform adjustment, which is required in the conventional example, is not necessary at all, and the adjustment work is not troublesome.

Also, the abnormality detection range can be set very easily because it is only necessary to change the magnitude of the DC voltage.

Moreover, an amplifier for waveform adjustment, etc., which was required in the conventional example
Since 10 and 14 and the complicated CR circuits 12 and 16 associated therewith are not necessary, the number of parts is small and the cost is low.

There are various ways to use the abnormal signal SA. For example, it may be used for an alarm display, or the ion implantation used for the interlock may be automatically stopped.

Further, instead of using the window comparator 32, two comparators and an OR circuit may be used if necessary.

Further, it is preferable to provide the buffer amplifier 30 as in this example in order to prevent interference, but depending on the circuit conditions (for example, impedance), the buffer amplifier 30 may not be provided.

Further, the differential amplification amplifier 4 may be omitted depending on the relationship with the gain of the voltage amplification circuit 6 (that is, the differential amplification amplifier 4 is included in the voltage amplification circuit 6). It may be seen as).

In addition, one signal source 2 is shared and another scanning power supply 34 with an abnormality detection circuit having the same circuit configuration as described above is provided.
From these sides, the scan voltage VS
May be output.

[Effect of device]

As described above, according to the present invention, it is not necessary to bother to create a signal similar to the output feedback signal for abnormality detection as in the conventional example. Therefore, the adjustment work becomes unnecessary.

Further, since the upper limit value and the lower limit value may be set by the DC voltage, the setting of the abnormality detection range becomes extremely easy.

Moreover, since the amplifier for waveform adjustment and the complicated CR circuit accompanying it which are required in the conventional example are not required, the number of parts is small and the cost is low.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a scanning power supply with an abnormality detecting circuit according to an embodiment of the present invention. FIG. 2 is a circuit diagram showing an example of a conventional scanning power supply with an abnormality detection circuit. 2 ... Signal source, 4 ... Differential amplification amplifier, 6 ... Voltage amplification circuit, 30 ... Puffer amplifier, 32 ... Window comparator, P ... Matching point, (S _i −S _o ) ... Difference.

Claims (1)

[Scope of utility model registration request] 1. A voltage amplifier circuit is provided, and a difference between a scanning signal including a triangular wave component given from a signal source and a feedback signal from an output portion of the voltage amplifier circuit is calculated, and the voltage amplifier circuit is controlled by this difference. Then, the scanning voltage is output therefrom, and the difference is compared with a predetermined upper limit value and a lower limit value in a comparison circuit, and when the difference is out of the range of the upper limit value and the lower limit value, A scanning power supply with an abnormality detection circuit characterized by outputting an abnormality signal from a comparison circuit