JPH0722852Y2 - Beam monitor for ion implanter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a beam monitor for an ion implantation apparatus.

(Prior Art) As is well known, in an electrostatic scanning type ion implantation apparatus, an ion beam is horizontally and vertically deflected and then is irradiated onto a target through a mask. In such an implanting device, observing the aperture state of the beam,
In addition, a monitor is attached for adjustment.

FIG. 5 shows a conventional beam monitor of this kind. Reference numeral 1 denotes an ion implanter, which is an ion beam accelerated by an accelerating tube (not shown).
Then, the target 5 is irradiated with the polarized light after passing through the mask 4.

6 is a vertical scanning power supply, which is constituted by a triangular wave generating circuit of about 500 Hz, and 7 is a horizontal scanning power supply,
For example, it is composed of a triangular wave generating circuit of about 100 Hz. Reference numeral 8 is an amplifier that detects and amplifies the beam current, and 9 is a display device for a monitor, which is composed of a cathode ray tube (CRT) or the like.

The output of the amplifier 8 is input to the display device 9 as a vertical deflection signal (Y), and the vertical and horizontal scanning power supplies 6 and 7 are connected to the electrodes 2 and 3, respectively.
And a horizontal deflection signal (X) to the display device 9 via the changeover switch 10.

As mentioned above, the ion beam is used for both vertical and horizontal scanning electrodes 2,3.
When passing between the respective electrodes, the electrodes are deflected by the triangular wave voltage applied from the power sources 6 and 7 between the respective electrodes. If the deflection angle at each electrode at this time is large, the mask 4
The beam impinges on the peripheral portion (which is usually formed in a circular hole) and cannot pass therethrough, and does not reach the target 5.

Assuming that the change-over switch 10 is connected to the horizontal scanning power supply 7 side, both surfaces of the display device 9 are as follows. That is, assuming that the beam is deflected to one side, for example, the left side, the beam hits the mask 4 and does not reach the target 5. Therefore, the curve representing the beam current of the display device 9 is enlarged and shown in FIG. As shown in the screen, the level is 0 at the left end.

As the beam moves toward the center of the mask 4 as the horizontal scanning progresses, the amount of the beam passing through the mask 4 gradually increases. This causes the beam current curve to rise with a slope. While the beam is passing through the hole of the mask 4, the curve becomes horizontal, and when the beam hits the right side of the mask 4, there is a downward inclination, and when the beam hits the right side of the mask 4, the curve becomes 0. It becomes a level.

Although the above description is for the case where the beam moves from the left side to the right side, the curve changes with the same tendency even when the beam moves from the right side to the left side. Further, in actuality, the scanning on the vertical side is also performed at the same time, so that the trapezoidal wave represented by the curve is divided into a larger number of trapezoidal waves. This will be specifically described as follows.

Figure 7 shows the trajectory of the beam sweeping on the mask. The vertical scanning frequency (about 500Hz) is about 5 times the horizontal scanning frequency (about 100Hz), and the trajectory on the mask is also vertical. The movement on the side is about 5 times faster.

Now, starting from the 0 point on the mask 4A, the beam hits the mask 4A up to the point 1 and the target current does not flow, but from the point 1 to the point 2 the beam passes through the hole 4 of the mask 4A. , The target current flows. In the same manner, the target current changes in the same manner, such that the target current changes from point 2 to point 3 and does not flow to point 4 but flows from point 4 to point 5.

FIG. 8 shows the vertical scanning signal, the horizontal scanning signal, and the beam current with the passage of time. Only when each scanning signal is in a relationship in which the beam can pass through the hole 4 of the mask 4A, The beam current is obtained, and the pulse waveform becomes irregular in width.

FIG. 9 shows the case where the beam current waveform is swept in synchronization with the horizontal scanning signal, and corresponds to the waveform when the changeover switch 10 of FIG. 5 is connected to the horizontal scanning power source 7 side. About 100 waveforms will appear to overlap due to the afterimage, but the envelopes of these waveforms will be as shown in Fig. 6 even if their positions are changed left and right. As described above, in this case, a screen in which a curve showing the beam current in the horizontal direction appears can be obtained.

The same applies when the changeover switch 10 is connected to the vertical scanning power source 6 side, and FIG. 10 shows the case where the beam current waveform is swept in synchronization with the vertical scanning signal. Corresponding to the waveform when 10 is connected to the vertical scanning power supply 6 side, about 100 waveforms will appear to overlap due to visual afterimages, but these will overlap in a substantially symmetrical shape on the left and right. , Its envelope becomes the shape shown in FIG. In this case, a screen in which a curve showing the beam current in the vertical direction appears is obtained.

By observing such a curve, the scanning range of the beam can be known, and by observing the inclined portions on both sides of the envelope of the curve, the adjustment of the beam can be known. For example, when the beam is narrowed down, the inclination becomes steep, and when the beam is thick, the inclination becomes gentle.

Therefore, the above-mentioned judgment is made by looking at the screen of the display device 9, and the respective parameters (vertical, horizontal offset,
The scan width, beam iris, etc.) are adjusted to perform the desired implant.

In this case, in particular, regarding the aperture of the beam, if the vertical aperture is made stronger, the horizontal aperture becomes weaker, and conversely, if the horizontal aperture is made stronger, the vertical aperture becomes weaker. Therefore, in order to obtain the optimum state in which the diaphragms in both directions are approximately the same, it is necessary to adjust the diaphragm while comparatively observing both the vertical screen and the horizontal screen.

However, in order to carry out such adjustment with the conventional configuration shown in FIG. 5, it is necessary to repeatedly switch the changeover switch 10 a number of times, and the operation thereof is extremely troublesome.

(Problems to be Solved by the Invention) The purpose of this invention is to make it possible to easily observe the state of the beam stop in both vertical and horizontal directions upon ion implantation.

(Means for Solving the Problems) The present invention is a signal switching circuit for periodically switching each vertical and horizontal scanning signal from a vertical scanning power source and a horizontal scanning power source as a horizontal deflection input of a display device and supplying the signal to the display device. An output corresponding to the beam current from the target and an output obtained by inverting or biasing the output are alternately applied to the display device as a vertical deflection input in synchronization with both the horizontal deflection signals. It is characterized by having done.

(Embodiment) An embodiment of the present invention will be described with reference to FIG. The fifth
Portions denoted by the same reference numerals as those in the figure indicate the same or corresponding portions. According to the present invention, in order to periodically apply the vertical scanning signal from the vertical scanning power source 6 and the horizontal scanning signal from the horizontal scanning power source 7 to the display device 9 as a horizontal deflection input (X) of the display device 9, A switching circuit 11 is prepared. This circuit 11 is switched by a switching signal (for example, a square wave signal of about 30 Hz) from the switching signal generating circuit 12.

Further, the output from the amplifier 8, that is, the output corresponding to the beam current and the output from the inverting circuit 13 which inverts the output and outputs it are alternately switched by the signal switching circuit 14, and the vertical deflection input of the display device 9 is obtained. Given as. The signal switching circuit 14 is switched by a switching signal from the switching signal generating circuit 12 so as to be switched in synchronization with the signal switching circuit 11.

In the above configuration, the signal switching circuit 11 inputs the vertical scanning signal from the vertical scanning power supply 6 to the horizontal deflection input (X) of the display device 9 while the output from the switching signal generating circuit 12 is not present.
Further, the signal switching circuit 14 gives the inverted output from the inverting circuit 13 as the vertical deflection input (Y) of the display device 9. Therefore, at this time, the second screen is displayed on the screen of the display device 9.
As shown in the figure, the downwardly facing waveform pattern (A) is drawn. Specifically, the waveform is a multiple waveform as shown in FIG. 10, but the envelope is as shown in the waveform figure (A) of FIG.

In addition, this downward waveform figure (A) is not always the same,
Although it changes in the X-axis direction depending on the horizontal scanning position of the beam, since the change is fast, the visual recognition as a whole is always the same, and it is recognized that it does not change.

While the output from the switching signal generating circuit 12 is present, the signal switching circuit 11 gives the horizontal scanning signal from the horizontal scanning power source 7 as the horizontal deflection input (X) of the display device 9, and the signal switching circuit 14 supplies the amplifier. The output of 8 is given as the vertical deflection input (Y) of the display device 9. Therefore, at this time, an upward waveform figure (B) is drawn on the screen of the display device 9 as shown in FIG. Specifically, the waveform figure (B) has multiple waveforms as shown in FIG. 9, but the envelope is the second waveform.
It becomes like the waveform figure (B) in the figure.

Both waveforms described above are the afterimage time of the human eye (about 0.1 seconds)
Since it can be switched at a faster cycle (about 0.03 seconds), both screens will be recognized as overlapping of about 50 waveforms, and both screens can be recognized as the same screen, horizontal and vertical directions. It becomes possible to simultaneously judge the states of both beams. That is, the waveform with the configuration of FIG. 5 is displayed as shown in FIG. 9 and FIG.
Although it is recognized as the waveform of FIG. 6 by superimposing about 100 pulse waveforms according to the visual afterimage time, in the configuration of FIG. 1, by superimposing about 50 pulses, the waveforms of A and B in FIG. However, since the switching frequency and the number of overlapping waveforms are sufficiently large, there is almost no effect on the recognition accuracy.

In the configuration of FIG. 1, one of the waveform figures is inverted to draw the image, however, instead of this, it is also possible to draw without inverting. FIG. 3 shows a configuration therefor. Instead of the inverting circuit 13 and the signal switching circuit 14, the output of the amplifier 8 and the square wave signal from the switching signal generating circuit 12 are added by an adder 15 , As a vertical deflection input (Y). Other configurations are the same as those in FIG.

During the period when the output from the switching signal generation circuit 12 does not exist, the signal switching circuit 11 outputs the vertical scanning signal from the vertical scanning power source 6 to
It is given as the horizontal deflection input (X) of the display device 9, and the output from the amplifier 8 is directly given as the vertical deflection input (Y) of the display device 9. Therefore, at this time, the waveform figure (A) as shown in FIG. 4 is drawn on the screen of the display device 9. Specifically, the waveform figure (A) has multiple waveforms as shown in FIG. 10, but the envelope is as shown in FIG. 4 (A).

While the output from the switching signal generating circuit 12 is present, the signal switching circuit 11 supplies the horizontal scanning signal from the horizontal scanning power source 7 as the horizontal deflection input (X) of the display device 9. The output of the switching signal generation circuit 12 and the output of the amplifier 8 are added by an adder.
Vertical deflection input (Y) of display device 9
Give as. Therefore, at this time, the waveform figure (B) shown in FIG. 4 is drawn on the screen of the display device 9.
This is a waveform in which the output of the amplifier 8 is biased in the positive direction by the output of the switching signal generating circuit 12.

Even in this case, since both waveform patterns can be switched at a cycle faster than the afterimage time of the human eye, both screens can be recognized as the same screen, and the state of both horizontal and vertical beams can be judged at the same time. Become.

(Effect of the Invention) As described in detail above, according to the present invention, the beam current waveforms in both the vertical and horizontal directions of the ion beam with which the target is irradiated are simultaneously displayed on the display device. It is possible to easily and surely judge the condition.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG.
FIG. 3 is a waveform diagram showing the waveform drawn by the display device shown in the figure by an envelope, FIG. 3 is a partial circuit diagram showing another embodiment of the present invention, and FIG. 4 is an envelope showing the waveform drawn by the display device shown in FIG. FIG. 5 is a waveform diagram shown by a line, FIG. 5 is a circuit diagram of a conventional example, FIG. 6 is a waveform diagram showing the waveform drawn by the display device of FIG. 5 by an envelope, and FIG. A locus diagram showing the locus, FIG. 8 is a waveform diagram showing the time course of the vertical scanning signal, the horizontal scanning signal, and the beam current, and FIG. 9 is a waveform when the beam current waveform is deflected and displayed in synchronization with the horizontal scanning signal. 6 and 2 are detailed waveform diagrams such as the waveform A of FIG. 2 and the waveform A of FIG. 4, and FIG. 10 is the waveform when the beam current waveform is deflected and displayed in synchronization with the vertical scanning signal. Details of waveform B in FIG. 2, FIG. 2 and waveform B in FIG. It is in the form view. DESCRIPTION OF SYMBOLS 1 ... Ion implantation device, 2 ... Vertical deflection electrode, 3 ... Horizontal deflection electrode, 4 ... Mask, 5 ... Target, 6 ... Vertical scanning power supply, 7 ... Horizontal scanning power supply, 9 ... Display device, 11, 14 ... Signal switching circuit , 12 ... Switching signal generation circuit, 13 ... Inversion circuit, 15 ... Adder,

Claims (1)

[Scope of utility model registration request] 1. A vertical scanning power supply and a horizontal scanning power supply for supplying scanning signals to the vertical deflection electrodes and the horizontal deflection electrodes of the ion implantation apparatus, and vertical and horizontal scanning signals from the respective power supplies are periodically used as horizontal deflection inputs. A signal switching circuit for selectively switching to a monitor display device, an output corresponding to a beam current obtained from a target of the ion implantation device, and an output obtained by inverting or biasing the output. A beam monitor for an ion implanter, which comprises a circuit for alternately providing a vertical deflection input to the display device in synchronization with a horizontal deflection signal.