JPS6235252Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a charged particle beam entry control device in an ion implantation apparatus using charged particle acceleration.

FIG. 1 schematically shows the relationship between a charged particle beam and a rotating target plate in an ion implantation apparatus using charged particle acceleration.

A plurality of wafer holding holes 2 are formed on the periphery of the rotating target plate 1, and the wafers to be ion-implanted are held by the stepped portions of the wafer holding holes 2. The rotating target plate 1 is rotated by a motor 4 engaged with its rotating shaft 3. If the wafer is held in the wafer holding hole 2, the rotating target plate 1 is translated in the direction of arrow b in a vacuum state, and the rotating target plate 1 is rotated at the same time,
Each wafer is implanted with an ion beam in the direction of arrow a.

In such a case, the motor 4 for rotating the rotary target plate 1 is driven by inputting a signal to an external motor control section 13.
The rotational speed and rotational speed fluctuation of the rotating target plate 1 were not measured.

By the way, when injecting charged particles into a wafer, the injection amount for each wafer held on the rotating target plate 1 is determined in advance, so the number of rotations of the rotating target plate 1 may exceed a required value. The injection time is determined based on this, but in the conventional apparatus, the rotational speed and rotational speed fluctuation of the rotating target plate 1 are not measured as described above. Therefore, in such a device, in order to start ion implantation, after driving the motor, a certain amount of extra time is allowed for obtaining the required rotation speed and the final rotation speed, and then the charged particle beam enters. To begin with, this extra time is lost time.

Therefore, in this invention, in order to eliminate this loss time, the rotation speed of the rotating target plate is detected,
The system is configured to open the shutter of the charged particle beam when the required rotational speed is reached.

The embodiments shown in the drawings will be described below.

FIG. 2 shows an embodiment of the present invention, in which a rotating target plate 1, a wafer holding hole 2, a rotating shaft 3, and a driving motor 4 engaged therewith have the same construction as that shown in FIG. A small hole 5 is formed on the periphery of the rotating target plate 1, and a light emitter 6 and a photoelectric converter 7 for receiving light are arranged integrally with the rotating target plate in the vertical direction of the small hole 5, respectively.
The output side of the photoelectric converter 7 is connected to a frequency meter 8, the output side of the frequency meter 8 is connected to a discrimination circuit 9 having a frequency preset function, and the output of the discrimination circuit 9 is controlled by the drive unit 11 of the beam shutter 10. can give a signal.

The light beam from the light emitter 6 is intermittently incident on the photoelectric converter 7 due to the rotation of the rotating target plate 1, where it is converted into an electrical quantity, the frequency is measured by a frequency meter, and this output is preset in the discrimination circuit 9. When the frequency is higher than or lower than the preset frequency, a signal is generated, and this signal drives the beam shutter 10 to direct the charged particle beam from the direction of the arrow to the rotating target. It is possible to enter and cover the plate 1 and to monitor the rotational speed of the rotating target plate 1.

Instead of the embodiment described above, as partially shown in FIG. 3, a light reflector 12 is provided on the lower surface of the rotary target plate 1, for example, without providing a small hole 5 for transmitting light in the rotary target plate 1. The light emitter 6 and the photoelectric converter 7 are arranged so that the light from the light emitter 6 is incident on the photoelectric converter 7 through the reflector 12, and the output side of the photoelectric converter 7 is already connected to the second If they are connected as explained in the embodiment shown in the figure, they will function in the same way, and the beam shutter 10 can control the charged particle beam in the direction of the arrow. Note that the rotating target plate 1 itself may be used as the reflector 12, and if a recurrent reflector is used as the reflector, a photoelectric device incorporating a light emitter and a photoelectric converter can be used. The arrangement of the light emitters and photoelectric converters does not extend above and below the rotating target plate 1 as in the embodiment shown in FIG. 1.

Fig. 4 shows the control position of the present invention with respect to the number of rotations of the rotating target plate 1. According to the conventional method, the loss time would be OA, but according to the present invention, the required frequency (number of rotations) is determined by a circuit. By presetting at , it is possible to reliably indicate the time when the required rotation is reached for injection, thereby reducing loss time to OB.

On the other hand, if the rotation speed of the rotating target plate 1 decreases during injection of the charged particle beam, the discrimination circuit 9 detects this and closes the beam shutter 10, thereby deteriorating the uniformity of the charged particle beam injection. can be prevented.

As described above, according to the present invention, loss time during charged particle beam implantation can be reduced and uniform ion implanted products can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram illustrating the relationship between a charged particle beam of an ion implantation apparatus using charged particle acceleration and a rotating target plate. FIG. 2 shows an embodiment of the present invention. FIG. 3 shows a part of the rotation speed detection device used in the present invention. FIG. 4 shows the control positions of the present invention and the conventional method with respect to the rotational speed of the rotating target plate. DESCRIPTION OF SYMBOLS 1...Rotating target plate, 2...Wafer holding hole, 3...Rotating shaft, 4...Motor, 5...Small hole provided in the rotating target plate, 6...Light emitter,
7... Photoreceptor (photoelectric conversion element), 8... Frequency meter, 9... Discrimination circuit, 10... Beam shutter, 11... Beam shutter drive unit, 12...
Reflector, 13...Motor control unit.

Claims (1)

[Scope of utility model registration request] A device is installed to measure the rotational speed of a rotating target plate in an ion implantation device using charged particle acceleration.
The number of rotations from the device is compared with a predetermined number of rotations, and when the number of rotations from the device becomes larger than the predetermined number of rotations, the charged particle beam shutter is opened, and the number of rotations from the device is higher than the predetermined number of rotations. A charged particle beam entry control device in an ion implantation apparatus, wherein the shutter is closed when the particle beam becomes small.