JPH0648737Y2 - Ion processing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] This invention irradiates an ion beam on a substrate mounted on a disk that can be rotated and translated in a vacuum container to ion-implant, ion-beam etch, etc. The present invention relates to an ion processing apparatus which performs processing and has a means for measuring and displaying a beam current density distribution of an ion beam.

[Conventional technology]

 A conventional example of this type of ion treatment apparatus is shown in FIG.

In a vacuum container (not shown), a disk 6 that is rotated by the disk drive device 8 as shown by arrow A and translated as shown by arrow B is housed, and a peripheral edge of the surface of the disk 6 is accommodated. A plurality of substrates (for example, wafers) 4 are mounted. Then, each substrate 4 is sequentially irradiated with the ion beam 2 guided from an ion source (not shown) or the like, and the substrate 4 is subjected to ion implantation, ion beam etching or the like.

The disk drive device 8 is a motor for rotating the disk 6.
It has a motor 12 for translating the disk 6 and the like through the mechanism 10 and the mechanism portion 14.

The translation speed v of the disk 6 is translated from the translation speed control device 16 to the disk drive device 8 (more specifically to the motor 12 thereof) in order to uniformly irradiate each substrate 4 on the disk 6 with the ion beam 2. Speed signal S ₁ (See Fig. 2 for its waveform)
Is controlled to satisfy the following relationship.

v∝I / R where I is the beam current of the ion beam 2 and is measured by a current measuring device 18 such as a current integrator electrically connected to the disk 6. R is disk 6
Is the distance between the center of rotation and the center of the ion beam 2.

On the other hand, in such an ion processing apparatus, since it is important to confirm the beam current density distribution of the ion beam 2, the following means are taken.

That is, a mask 20 having a plurality of (three in the illustrated example, but not limited to) holes 21 arranged in a substantially straight line is provided at a position located behind the disk 6 in the irradiation region of the ion beam 2,
Further, a collector electrode 22 is provided on the rear side of each hole 21. Therefore, when measuring the beam current density distribution of the ion beam 2, the disk 6 is retracted to a position where it does not interfere with it.

A beam current measuring resistor 24 is connected to each collector electrode 22, and a voltage signal corresponding to the beam current flowing therethrough is generated at both ends thereof. Then, this voltage signal is selectively switched by a switch circuit (for example, an analog switch) 26 having a plurality of switching elements 27 and is given to an isolation amplifier 28, and further to a Y-axis terminal 32 of a display device 30 such as an oscilloscope. Is entered.

Switching of the switch circuit 26 is performed as follows. That is, a pulse is generated by the pulse generator 33 and this pulse is input to the counter 34. The counter 34 counts the input pulses (up-counting and down-counting are repeated), and the output thereof is the above-mentioned switch circuit 26.
And the input signal of the D / A converter 36. Therefore, the triangular wave signal S ₂ is obtained at the output of the D / A converter 36, and this is input to the X-axis terminal 31 of the display device 30.

Therefore, in the display device 30, for example, as shown in FIG. 6, the beam current densities of the ion beams 2 detected by the collector electrodes 22 are displayed at the positions corresponding to the arrangement of the collector electrodes 22, respectively.

[Problems to be solved by the device]

However, in the above device, the substrate 4 on the disk 6 is
However, there is a problem that the beam current density distribution of the ion beam 2 being processed cannot be measured. This is because the mask 20 and collector electrode 22 are behind the disk 6 during processing of the substrate 4.

There is also a problem that a special structure such as the mask 20 and the collector electrode 22 must be provided on the rear side of the disk 6 in order to measure the beam current density distribution.

Further, since the number of collector electrodes 22 cannot be increased so much due to dimensional restrictions, there is a problem that the number of measurement points is small and therefore the beam current density distribution can be measured only roughly.

Then, this invention aims at providing the ion treatment apparatus which improved such a point.

(Means for Solving the Problem) The ion treatment device of the present invention outputs an absolute value amplifier for obtaining an absolute value of a translational speed signal output from the translational speed control device as described above, and an output from this absolute value amplifier. A voltage / frequency converter for converting a signal into a frequency, a polarity discriminator for discriminating the polarity of the translation speed signal, and a signal output from the voltage / frequency converter in response to a signal output from the polarity discriminator. A counter that counts the frequency in a predetermined direction when the translation speed signal is positive and in the opposite direction when the translation speed signal is negative, a D / A converter that converts the signal output from this counter to analog, and the disk. Beam current measuring device for measuring the beam current flowing through the beam, and sample and hold of the signal output from the beam current measuring device in response to the signal output from the voltage / frequency converter A sample and hold circuit, a differential amplifier that obtains the difference between the input signal and the output signal of this sample and hold circuit, and the magnitude of the signal output from this differential amplifier to the signal output from the D / A converter. It is characterized by comprising a display device for displaying at a corresponding position.

[Action]

The absolute value of the translational speed signal is determined by the absolute value amplifier, which is converted into a frequency by the voltage / frequency converter, which is up-counted or down-counted by the counter depending on the polarity of the translational speed signal, and its output is D The / A converter converts the analog signal into an analog signal, which is applied to the display device as a signal for controlling the display position.

On the other hand, when the disk translates and its end enters the irradiation area of the beam current, a beam current flows through the disk current, which is measured by the beam current measuring device, and the signal output therefrom is sampled and held by the voltage / frequency converter. It is sampled and held in response to the signal output from. Then, the difference between the input and output signals of the sample hold circuit is obtained by the differential amplifier, and this difference corresponds to the beam current in a certain minute area of the ion beam at the end of the disk.

Then, the magnitude of the beam current is displayed on the display device at a position corresponding to the triangular wave signal. As a result, the beam current density distribution of the ion beam is displayed on the display device.

〔Example〕

FIG. 1 is a diagram showing an ion processing apparatus according to an embodiment of the present invention. The same or corresponding parts as those in the example of FIG. 5 are designated by the same reference numerals, and the differences from the conventional example will be mainly described below.

In this embodiment, the X of the display device 50 is as follows.
The triangular wave signal S ₃ supplied to the shaft terminal 52 is produced.

That is, first, the absolute value amplifier 56 obtains the absolute value of the translational speed signal S ₁ output from the translational speed control device 16 as described above. This is because, as shown in FIG. 2, the translational speed signal S ₁ is reversed in polarity between the forward path and the return path in order to reciprocally translate the disk 6, so that the voltage / frequency converter 58 can be used to reverse it. This is because the signal on the return path is inverted to the positive side as shown by the broken line so that the signal can be converted.

Further, in order to reverse the direction of counting by the counter 60 to be described later in accordance with the polarity inversion of the translation speed signals S _1, so that a polar discriminator 64 discriminates the polarity of the translational velocity signal S _1.

Then, the signal output from the absolute value amplifier 56 is converted into a frequency by the voltage / frequency converter 58, and the frequency is converted by the counter 60 when the translation speed signal S ₁ is positive (that is, the disk 6 is translating in the forward path). Is up-counted, and is down-counted when the translational speed signal S ₁ is negative (that is, the disk 6 is translating in the return path). Therefore, when the output of the counter 60 is converted into analog by the D / A converter 62, a triangular wave signal S ₃ that rises while the disk 6 is translating in the forward path and falls while the disk 6 is in the return path is obtained. Then, this is input to the X-axis terminal 52 of the display device 50 such as an oscilloscope as a signal for controlling the display position.

On the other hand, in this embodiment, unlike the conventional example, it is not necessary to provide a special structure for measuring the beam current density distribution of the ion beam 2, and instead, the path of the beam current I flowing through the disk 6 is provided. A beam current measuring resistor 38 is inserted as a beam current measuring device, and a voltage signal across the resistor 38 is input to a sample hold circuit 42 via an insulating amplifier 40.

The sample-hold circuit 42 is a known one, and includes two amplifiers 43 and 44 and a switching element 45 inserted between them.
And a hold capacitor 46. The switching element 45 is connected to the voltage / frequency converter 58 described above.
It is turned on and off by a frequency signal output from the sample operation (when the switching element 45 is on) and the hold operation (when the switching element 45 is off).

Then, the difference between the input signal of the sample hold circuit 42 (which is equivalent to the output signal of the amplifier 43) and the output signal is obtained by the differential amplifier 48, and the output is input to the Y-axis terminal 54 of the display device 50. I am trying to do it. If this is done, the output of the differential amplifier 48 will be the disk 6 for the following reasons.
Corresponds to the beam current in a certain minute region of the ion beam 2 at the end of the.

That is, referring to FIG. 3, assuming that the disk 6 is now translating in the forward direction in the direction of the arrow B, the end portion of the disk 6 eventually becomes the irradiation region of the ion beam 2 as shown by the solid line in the figure. A part of the beam current of the ion beam 2 flows into the disk 6 when it enters.

If the value of the beam current at time T ₁ is sampled and held in the sample hold circuit 42, the disk 6 is continuously translated, so that the sample hold circuit
At the time T ₂ when 42 next samples and holds, the disk 6 advances slightly as indicated by the chain double-dashed line in the figure, so that between the times T ₁ and T ₂ , the ion beam 2 is transferred to the disk 6.
There is a difference of ΔS (hatched portion in the figure) in the area corresponding to. Therefore, if the difference between the value of the beam current at time T ₁ and the value of the beam current at time T ₂ previously held is calculated by the differential amplifier 48, the above Δ of the ion beam 2 is obtained.
The beam current of the portion in the S region is obtained.

Moreover, this ΔS is always constant because the sampling operation and the holding operation in the sample-hold circuit 42 are switched at a frequency according to the magnitude of the translation speed signal S ₁ (that is, the translation speed v of the disk 6). If the frequency is increased, the area becomes minute.

Then, the beam current, ie, the beam current density, in the constant minute region of the ion beam 2 obtained as described above is displayed on the display device 50, and the display device displays the triangular wave output from the D / A converter. The position corresponds to the signal S ₃ , that is, the position where the beam current density is measured as described above.

Therefore, if the sample-hold operation as described above is continued, the beam current density distribution of the ion beam 2, for example, as shown in FIG. 4 is displayed on the display device 50 in real time.

[Effect of device]

As described above, according to the present invention, it is not necessary to provide a special structure for measuring the beam current density distribution of the ion beam, unlike the conventional example.

Moreover, since the disk is used as it is as a part of the measuring means, the beam current density distribution during processing of the substrate on the disk can be measured and displayed in real time on the disk surface to be actually processed.

Moreover, since the measurement region can be subdivided according to the frequency output from the voltage / frequency converter, the beam current density distribution can be measured very finely.

[Brief description of drawings]

FIG. 1 is a diagram showing an ion processing apparatus according to an embodiment of the present invention. FIG. 2 is a diagram showing an example of the waveform of the translational speed signal. FIG. 3 is a plan view showing an example of the relationship between the disk and the ion beam. FIG. 4 is a diagram showing an example of the beam current density distribution measured by the apparatus of this embodiment. FIG. 5 is a diagram showing an example of a conventional ion treatment apparatus. FIG. 6 is a diagram showing an example of a beam current density distribution measured by a conventional device. 2 ... Ion beam, 4 ... Substrate, 6 ... Disk, 8
...... Disk drive device, 16 ・ ・ ・ Translation speed control device, 38 ・ ・ ・
… Beam current measurement resistance, 42 …… Sample and hold circuit,
48 ... Differential amplifier, 50 ... Display device, 56 ... Absolute value amplifier, 58 ... Voltage / frequency converter, 60 ... Counter, 62 ...
… D / A converter, 64 …… Polarity discriminator, S ₁ …… Translation speed signal.

Claims (1)

[Scope of utility model registration request] 1. A disk, which is housed in a vacuum container and on which a plurality of substrates are mounted, a disk drive device for rotating and translating the disk, and a translation speed signal given to the disk drive device. In a device for irradiating each substrate on a disk with an ion beam and processing them, an absolute value amplifier for obtaining an absolute value of a translational speed signal output from the translational speed control device. A voltage / frequency converter for converting the signal output from the absolute value amplifier into a frequency, a polarity discriminator for discriminating the polarity of the translational speed signal, and a signal output from the polarity discriminator in response to the polarity discriminator. A counter for counting the frequency output from the voltage / frequency converter in a predetermined direction when the translation speed signal is positive and in the opposite direction when the translation speed signal is negative; D / A converter for converting the signal output from the counter to analog, a beam current measuring device for measuring the beam current flowing through the disk, and a signal output from the beam current measuring device for the voltage / frequency converter A sample and hold circuit that samples and holds in response to a signal output from the differential amplifier, a differential amplifier that obtains the difference between the input signal and the output signal of the sample and hold circuit, and the magnitude of the signal output from the differential amplifier. An ion processing apparatus comprising: a display device that displays a position corresponding to a signal output from a D / A converter.