JPS63953A - Ion radiating device - Google Patents

Abstract

PURPOSE:To reduce the temperature rise and the like of a base plate, by furnishing the first correcting device to amplify the beam current at a specific magnification and the second correcting device to keep the dosage constant to an ion radiating device of the mechanical scanning method. CONSTITUTION:A disk 4 is translated by a motor 12 while it is rotated by a motor 10, and the ion beam 2 is radiated in order on plural base plates 6 loaded on the disk 4. In this case, a beam current I is amplified by a correcting circuit 18 at a specific magnification and fed to an ampere meter 14, and the translation is controlled by the generated pulse through a control circuit 16. And, depending on the then magnification, the control circuit 16 is controlled by a correction circuit 20, to keep constant the dosage which is variable with the magnification change. Therefore, the translation speed can be made larger even though the beam current is smaller, and a charge up, a temperature rise, and the like of the base plate 6 can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] This invention relates to a method for irradiating an ion beam onto a substrate mounted on a disk that is rotated and translated within a vacuum container.
The present invention relates to a so-called mechanical scan type ion irradiation device, and particularly to improvements in disk translational movement control.

[Conventional technology]

Ion irradiation devices include ion implantation devices, ion beam etching devices, ion evaporation thin film forming devices that use both ion implantation and vacuum deposition, and the like. In the following, an ion implantation device will be explained as an example.

FIG. 2 is a schematic diagram showing an example of a conventional mechanical scan method ion implantation apparatus. Vacuum container (not shown)
A disk 4 is provided therein, which is rotated at high speed as shown by arrow A and translated as shown by arrow B by a mechanism to be described later. is installed. Then, each substrate 6 is sequentially irradiated with an ion beam 2 from an ion source (not shown) to process the substrate 6, for example, to perform ion implantation.

Disk 4 is a motor (e.g. induction motor)
10 via the mechanism section 8 as described above, and a motor (for example, a stethobbing motor) 12
is translated as described above via the mechanism section 8.

In that case, the control circuit 16 controls the translational movement of the disk 4.
This is done as follows. That is, in order to uniformly irradiate each substrate 6 on the disk 4 with the ion beam 2, the translational velocity (2) of the disk 4 is controlled so as to satisfy the following relationship.

V<I/R... (1) Here,
■ is the beam current of ion beam 2, R is ion beam 2
is the distance between the center of the disk 4 and the center of the disk 4.

The control circuit 16 also controls the number N of reciprocating translations of the disk 4 so that the dose (ion implantation amount) for each substrate 6 becomes a predetermined dose φ.

[Problem that the invention seeks to solve]

In the above ion implantation apparatus, the control circuit 16 specifically calculates the translational velocity of the disk 4 based on the signal of the number of pulses Q proportional to the beam current given from the current measuring device 14 as shown in the following equation. control.

V<Q/R... (2)
In that case, the current measuring device 14 is configured such that the measurement ranges are roughly switched in order to measure current in a wide range (for example, 300 nA to 30 mA), and the number of pulses Q of the signal output from it is set to the full range of each range. A signal whose scale is set to a predetermined number of pulses, for example 1000 PPS, is output. Therefore, for example, if the actual beam current ■ is 5 mA in the 10 mA range, Q = 500, and the disk 4
The translational velocity V becomes considerably slow (of course, even in that case, the relationship in equation (2) is satisfied).

However, the slower the translation speed V of the disk 4, the faster the substrate 6
A certain part of the upper part will be exposed to the ion beam 2 for a long time, and a problem arises in that the charge absorption and temperature rise of that part will increase, and the damage to the base plate 6 will increase.

SUMMARY OF THE INVENTION An object of the present invention is to provide an ion irradiation device that can increase the speed of translational movement of a disk even when the beam current is small.

Means for Solving Problem c] The ion irradiation device of the present invention is a device for irradiating an ion beam onto a substrate mounted on a disk that is rotated and translated in a vacuum container, and is capable of controlling the translation speed of the disk. Translation of the disk is controlled to be proportional to the beam current of the ion beam and inversely proportional to the distance from the center of rotation of the disk to the irradiation position of the disk with the ion beam, and to maintain a predetermined dose of the ion beam relative to the base material. In the device equipped with a control means for controlling the number of times, the above-mentioned control? a first correction means for correcting the beam current of the ion beam applied to the In means or a signal proportional thereto to a larger one by a predetermined magnification; It is characterized by comprising a second correction means for correcting the number of translations of the disk so that it does not change from the predetermined value regardless of the correction.

[Effect]

When the beam current is small, the first correction means can correct the beam current given to the control means or a signal proportional thereto to a large one by a predetermined magnification, thereby increasing the translational speed of the disk. Ru. on the other hand,
If the translation speed of the disk is simply increased, the dose amount to the substrate will decrease from a predetermined value, but in the present invention, this is prevented by the second correction means.

〔Example〕

FIG. 1 is a schematic diagram showing a mechanical scan type ion implantation apparatus according to an embodiment of the present invention. Components that are the same or equivalent to those in FIG. 2 are given the same reference numerals and their explanations will be omitted.

In this embodiment, the first
A correction circuit 18 is provided to correct the beam current I of the ion beam 2 to a larger value (+') by a predetermined magnification and provide the corrected beam current I to the current measuring device 14 described above. The magnification in this correction circuit 18 is set to a desired value by a magnification setter 22.

For example, when correcting the A% of a certain range of the current measuring device 14 to full output, the magnification setting device 22
A is set. As a result, the beam current I' given to the current measuring device l4 is 1' = (1 0 0/A)
l ... (3), and as a result, the number of pulses Q' of the signal output from the current measuring device 14 is also Q' = (1 0 0/A) Q ... (4
). As described above, this Q is the number of pulses at full scale in each range of the current measuring device 14, and is, for example, IOOOPPS/full scale.

Then, the control circuit 16 performs control according to equation (2) above based on this pulse number Q'. Therefore, for example, current measuring device 1
When the range of 4 is lomA and the actual beam current 2 is 5 mA, if A is set to 50%, the translational speed 2 of the disk 4 is 100/A=2 times that of the conventional case.

On the other hand, as mentioned above, the translational speed ■ of the disk 4 is set to 10
When correcting by 0/A times, the number of reciprocating translations of the disk 4 N
As it is, the predetermined dose φ for each substrate 6 cannot be obtained (that is, the dose becomes A/100 times the predetermined dose), so in this embodiment, a second correction circuit 20 is provided to correct it. I have to. That is, the correction circuit 20 adjusts the magnification to 100/100 set by the magnification setter 22.
Based on A, the number of reciprocating translations of the disk 4 is N'
= (1 0 0/A) N... Correct to (5) or the nearest integer. In this case, if the value of equation (5) is not an integer and you want to correct it to the nearest integer,
The proportionality coefficient of equation (2) that determines the translational velocity (■) of the disk 4 is slightly corrected. As a result, the dose amount for the substrate 6 is maintained at the predetermined dose amount φ, regardless of the corrections as in equations (3) and (4) above.

The interlock circuit 24 monitors the number of pulses Q' from the current measuring device 14, and determines whether it is the maximum allowable value determined by the mechanical limit of the translation mechanism of the disk 4 and/or the minimum allowable value determined by the injection conditions etc. If the value is exceeded, the control circuit 16 and the like are controlled to stop the translation of the disk 4, the irradiation of the ion beam 2, etc., and although it is preferable to provide it, it is not essential.

According to the above configuration, even when the beam current I of the ion beam 2 is small, that is, the ratio of the beam current I to the predetermined range of the current measuring device 14 is small, the dose amount for the base 6 can be kept at a predetermined value. The translational speed V of the disk 4 can be increased while maintaining the same speed. In other words, various translation speeds can be selected for the same Dawes world. As a result, it is also possible to reduce the charge absorption and temperature rise of the substrate 6 as described above. Further, even when the beam current I has a low ratio in a certain range, the number of pulses Q' supplied to the control circuit 16 increases and the resolution improves, so the control accuracy of the translational speed (2) of the disk 4 improves. You can also expect

Incidentally, instead of providing the correction circuit 18 as described above on the person J side of the current measuring device 14, a correction circuit that performs the correction as shown in equation (4) above may be provided on the output side of the current measuring device 14. A similar effect can be obtained.

Furthermore, although the above description has been made using an ion implantation device as an example, the present invention is not limited thereto, and can be widely applied to ion irradiation devices of the mechanical scan type, such as the one illustrated at the beginning. Of course.

〔Effect of the invention〕

As described above, according to the present invention, even when the beam current is small, the translation speed of the disk can be increased while maintaining the dose amount to the substrate at a predetermined value. As a result, it is also possible to reduce the charge amplifier and temperature rise of the substrate.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a mechanical scan type ion implantation apparatus according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing an example of a conventional mechanical scan type ion implantation apparatus. 2. ．． ．． Ion beam, 4...disk, 6...substrate, 14...current measuring device, 16...control? il1 circuit, 1st...first correction circuit, 20...second correction circuit, 22...magnification setter.

Claims (1)

[Claims] (1) A device that irradiates an ion beam onto a substrate mounted on a disk that is rotated and translated in a vacuum chamber, in which the speed of translational movement of the disk is proportional to the beam current of the ion beam, and the ion beam is irradiated from the center of rotation of the disk. A control means for controlling the number of translations of the disk so that it is inversely proportional to the distance of the beam to the disk irradiation position and so that the dose of the ion beam to the substrate becomes a predetermined value, wherein: a first correction means for correcting the beam current of the ion beam or a signal proportional thereto to a larger one by a predetermined magnification; and controlling the control means based on the magnification so that the dose amount to the substrate is adjusted regardless of the correction. and second correction means for correcting the number of translations of the disk so that it does not change from the predetermined value.