JPH04221784A - Beam current density distribution measuring device - Google Patents

Abstract

PURPOSE:To measure in details beam current density distribution of ion beam. CONSTITUTION:A plurality of collector electrodes 6 are arranged in the shape of a matrix in an irradiation region of ion beams. Each line is divided into a right and a left half. A measurement signal responding to a beam current flowing to each line of each half is selectively switched by means of switching circuits 12 and 14 controlled by means of a switch control circuit 30 to output. Beam current density of ion beam measured on the line is displayed on a display device 28 and in a position located facing the each line of a collector electrode 6.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a beam current density distribution measuring device for measuring and displaying the beam current density distribution of an ion beam, which is used in ion processing equipment such as ion implantation equipment and ion beam etching equipment. .

0002

[Prior Art] For example, in an ion implantation system, in order to reduce charge-up of a wafer,
It is important to make the beam current density distribution of the ion beam irradiated onto the wafer as uniform as possible and to widen the width of the distribution.

To do this, it is first necessary to measure the beam current density distribution of the ion beam, and a conventional beam current density distribution measurement device for this purpose has a plurality of collectors in the irradiation area of the ion beam 2, as shown in FIG. The electrodes 6 are arranged in a cross shape, and the beam current flowing through them is measured and displayed as a beam current density distribution on a display device (for example, an oscilloscope). 4 in the figure is a catch plate that catches the ion beam 2 traveling from the front side to the back side of the paper, and each collector electrode 6 is connected to this catch plate 4.
They are arranged in a cross shape on the front side.

0004

[Problems to be Solved by the Invention] However, in the conventional beam current density distribution measurement device as described above, the ion beam 2 having a two-dimensional spread is measured only in a cross shape. The problem is that the distribution is not known. Therefore, for example, even if the center of the ion beam 2 is shifted from the center of the catch plate 4, it is not obvious.

[0005] Therefore, the main object of the present invention is to provide a beam current density distribution measuring device that can measure the beam current density distribution in detail.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the beam current density distribution measuring device of the present invention has a plurality of collector electrodes arranged in a matrix in an ion beam irradiation area, and the right half of each row. and the left half are electrically connected in parallel, and a conversion circuit that generates a measurement signal corresponding to the beam current flowing in each row connected in parallel; A first switching circuit that switches and outputs the measurement signal, a second switching circuit that selectively switches and outputs the measurement signal of each row in the other half, and a measurement signal that reverses the polarity of the measurement signal output from the first switching circuit. A polarity-inverting amplifier that outputs the measurement signal output from the second switching circuit with the polarity reversed, and a polarity-inverting amplifier that outputs the measurement signal output from the second switching circuit without changing the polarity. the first and second switching circuits are controlled to correspond to each other in the same row according to the output from the counter; and controls the third switching circuit to switch to the polarity-inverting amplifier side when counting in one direction and to switch to the polarity-inverting amplifier side when counting in the other direction. a switching control circuit;
The present invention is characterized by comprising a display device that displays the signal output from the third switching circuit at a position corresponding to the position signal from the switching control circuit.

[0007]

[Operation] According to the above structure, when the first and second switching circuits are switched for each row by the switching control circuit while ion beams are irradiated onto a plurality of collector electrodes, the display device , the beam current density of the ion beam measured in that row is displayed at a position corresponding to each row of the collector electrode. This allows us to understand the beam current density distribution of the ion beam in detail.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing a beam current density distribution measuring device according to an embodiment of the present invention. FIG. 2 is a plan view showing an example of the arrangement of collector electrodes in FIG. 1.

In this embodiment, as shown in FIG. 2, a plurality of collector electrodes 6 are arranged in a matrix in the XY direction in the irradiation area of the ion beam 2, that is, in front of the catch plate 4 as described above. are doing.

In this embodiment, the collector electrode 6 is divided into a right half and a left half on the center line, and as shown in FIG. 1, the collector electrodes 6 in each row of the right half are electrically connected in parallel. , are connected to each switching element 12a of the first switching circuit 12, and are respectively connected to a resistor 8 constituting a conversion circuit that generates a measurement signal (voltage signal) corresponding to the beam current flowing in each row connected in parallel. are doing. In this example, each resistor 8 is connected to ground via a beam current measuring device 10 (the same applies to other resistors 8 to be described later). The switching circuit 12 selectively switches and outputs measurement signals generated in the resistors 8 in each row under the control of a switching control circuit 30 to be described later.

Similarly, the collector electrodes 6 in each row of the left half are electrically connected in parallel to each switching element 14a of the second switching circuit 14, and are also connected to the same resistor 8 as described above. Connected. This switching circuit 14 also selectively switches and outputs the measurement signals generated in the resistors 8 in each row under the control of the switching control circuit 30.

Furthermore, in this embodiment, the collector electrode 6 on the center line is connected to each switching element 13a of the fourth switching circuit 13, and the same resistor 8 as described above is connected.
are connected to each. This switching circuit 13 also selectively switches and outputs the measurement signals generated in each resistor 8 under the control of the switching control circuit 30.

The switching control circuit 30 includes a pulse generator 32 that generates pulses of a predetermined frequency, and counts these pulses (repeating up-counting and down-counting).
, an up/down counter 34 that outputs a position signal S1 indicating which switching element 12a-14a of the switching circuits 12-14 is to be turned on, an interface 36 for insulation, etc., and an interface 36 for each switching circuit 12-14 based on the position signal S1. switching elements 12a to 14
It has a decoder 38 that selectively and sequentially switches on the signals a corresponding to each row.

The switching control circuit 30 further includes the decoder 3
8, and a D/D converter which converts the signal from the decoder 40 into an analog signal and outputs a triangular wave signal S2.
It is equipped with an A converter 42, and this triangular wave signal S2 is input to the x-axis terminal of a display device (for example, an oscilloscope) 28.

The output from the switching circuit 12 is inputted via the measurement amplifier 18 to the normal polarity inverting amplifier 22 which outputs the output without inverting the polarity. switching circuit 14
The output is inputted via the measurement amplifier 20 to a polarity inversion amplifier 24 which inverts the polarity and outputs the output. The output from the switching circuit 13 is transmitted to the measurement amplifiers 18 and 20.
Via the measurement amplifier 16 whose gain is 1/2 compared to
It is input to a polarity normal rotation amplifier 22 and a polarity inversion amplifier 24. That is, the output from the switching circuit 13 is divided into halves and divided into the output from the switching circuit 12 and the output from the switching circuit 14 through the amplifiers 22 and 24.
are added respectively.

The output from the polarity normal rotation amplifier 22 and the output from the polarity inversion amplifier 24 are transferred to a third switching circuit 2.
6 is selectively switched and output, and this is input to the y-axis terminal of the display device 28. This switching circuit 26 receives a signal S3 from the switching control circuit 30 (more specifically from its up/down counter 34).
In response to this, the output is switched to the polarity-inverting amplifier 22 side during amplifier counting, and is switched to the polarity-inverting amplifier 24 side during down-counting.

According to the above configuration, when the collector electrode 6 is irradiated with the ion beam 2, the switching control circuit 30
When the switching circuits 12 to 14 are switched for each row of the collector electrode 6, the beam current density of the ion beam 2 measured in that row is displayed on the display device 28 at a position corresponding to each row of the collector electrode 6. Ru.

That is, when the up/down counter 34 is counting amplifiers, the switching circuit 26 has switched to the normal polarity amplifier 22 side, so that the beam measured between the collector electrode 6 on the center line and the collector electrode 6 on the right half The current density is displayed for each row on the display device 28, for example, as shown in FIG. 3, with the x-axis direction representing the position of each row of the collector electrode 6, and the y-axis direction representing the beam current density. The hatched area in the figure is the beam current density measured at the collector electrode 6 on the center line.

When the up/down counter 34 is counting down, the switching circuit 26 is switched to the polarity inverting amplifier 24 side, so the beam current density measured between the collector electrode 6 on the center line and the right half collector electrode 6 is , for each row, the x-axis direction is displayed as the position of each row of the collector electrode 6, and the y-axis direction is displayed as the beam current density, as shown in FIG. 4, for example, on the display device 28. The hatched area in the figure is the beam current density measured at the collector electrode 6 on the center line.

Therefore, if this is repeated at a certain period, a beam current density distribution as shown in FIG. 5, which is a combination of FIGS. 3 and 4, will be displayed on the display device 28. In this example, the beam current density of the ion beam 2 is
It is shown that the distribution is almost symmetrical both in the vertical direction (Y direction) and in the horizontal direction (X direction) with the center O (see FIG. 2) as the center.

On the other hand, for example, if the center of the ion beam 2 (the part with the highest density) is shifted to the right of the center O in FIG. 2, then in FIG. If the center of the ion beam 2 is shifted below the center O in FIG. 2, the peak on the right side of the y-axis will be higher than the mountain on the left side in FIG.

As described above, according to this beam current density distribution measuring device, since the two-dimensional beam current density distribution of the ion beam 2 can be determined, it is possible to measure the beam current density distribution in more detail than in the conventional example. It is possible to measure a distribution closer to the state of .

The number of collector electrodes 6 to be arranged in a matrix is not limited to the illustrated example and may be determined arbitrarily depending on, for example, the shape of the ion beam 2, the roughness of the measurement, etc. All you have to do is decide.

Further, the collector electrode 6 may not be placed on the center line as in the above example, but may be placed very close to the center line across the center line. The resistor 8, switching circuit 13, and measurement amplifier 16 are no longer necessary.

[0025]

[Effects of the Invention] As described above, according to the present invention, the two-dimensional beam current density distribution of the ion beam can be determined.
The beam current density distribution can be measured in more detail than in the conventional example, and a distribution closer to the actual state can be measured.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a beam current density distribution measuring device according to an embodiment of the present invention.

2 is a plan view showing an example of the arrangement of collector electrodes in FIG. 1. FIG.

FIG. 3 is a diagram showing an example of the beam current density distribution obtained on the center line and on the right half of the collector electrode.

FIG. 4 is a diagram showing an example of the beam current density distribution obtained at the collector electrode on the center line and in the left half.

5 is a diagram showing an example of a beam current density distribution obtained with the apparatus of FIG. 1. FIG.

FIG. 6 is a diagram showing the arrangement of collector electrodes of a conventional beam current density distribution measuring device.

[Explanation of symbols]

2 Ion beam 6 Collector electrode 8 Resistor 12 First switching circuit 14 Second switching circuit 22　Normal polarity amplifier 24 Polarity inversion amplifier 26 Third switching circuit 28 Display device 30 Switching control circuit

Claims (1)

[Claims] Claim 1: A plurality of collector electrodes arranged in a matrix in an ion beam irradiation area, the right half and left half of each row being electrically connected in parallel, and each row connected in parallel. A conversion circuit that generates measurement signals corresponding to the flowing beam current, and a first circuit that selectively switches and outputs the measurement signals of each half row.
a second switching circuit that selectively switches and outputs the measurement signals of each row in the other half;
a polarity normal amplifier that outputs the measurement signal output from the first switching circuit without reversing the polarity; a polarity inversion amplifier that outputs the measurement signal output from the second switching circuit with the polarity inverted; It includes a third switching circuit that selectively switches the output between the normal polarity amplifier side and the polarity inverting amplifier side, and an up/down counter, and the first and second switching circuits are configured to operate according to the output from the counter. The switching is controlled in correspondence to each row, and a position signal representing the switching position is generated, and when counting in one direction, the third switching circuit is switched to the polarity normal amplifier side to count in the other direction. a switching control circuit that controls the switch to switch to the polarity inverting amplifier side when A beam current density distribution measuring device comprising: