JPS63128540A - Ion implanting apparatus - Google Patents

Abstract

PURPOSE:To prevent occurrence of an error resulting form the beam variation of the ion implanting amount almost perfectly, by measuring the beam current of ion beams every moment, finding and storing the x-y distribution of the actual ion implanting amount depending on the resultant measurement, comparing the result with the x-y distrubution of the object implanting amount, and carrying out the sweep control of ion beams. CONSTITUTION:The device is furnished with a beam current measuring device d to measure the beam current of ion beams B, the first memory device e to store the resultant measurements one by one responding to the sweeping position of the ion beams B and memorize the x-y distribution of the actual ion implanting amount onto the target b, the second memory device f to store the preset x-y distribution of the object ion implanting amount onto the target b, and a control device g to give a control signal to a sweep device c depending on the comparison result of the data of the first and the second memory devices e and f to the respective x-y coordinates. And the sweeping position of the ion beams B is controlled to make the x-y distribution of the actual ion implanting amount equal to that of the object ion implanting amount. In such a way, the implanting concn. can be controlled constantly to be at the objectimplanting concn. accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an ion implantation apparatus for implanting dopants into semiconductors, metal materials, and the like.

<Prior Art> In an ion implantation apparatus, generally, an ion beam is accelerated by a DC high voltage power supply, and the ion beam is swept by an electromagnetic field or mechanical method and is implanted into a target such as a semiconductor.

In conventional ion implantation equipment, for example,
No. 145646, in order to keep the dopant implantation concentration per unit area constant, the period (510 m5ec) is sufficiently faster than the temporal change of the ion beam current.
) to sweep the ion beam uniformly over the target.

<Problems to be Solved by the Invention> However, according to the conventional methods described above, active control such as feedback control is not performed on changes in the ion beam current, and therefore the sweep cannot be completely controlled. Even if the ion beam current is uniform, if the temporal change in the ion beam current is steep, an implantation error will inevitably occur.

Furthermore, in recent years, it has been desired to implant an ion beam with higher energy than before into a larger target than before. In this case, the area to be swept becomes larger, and the electromagnetic field or mechanical energy required for sweeping also becomes larger. However, since there is a limit to the electromagnetic field or mechanical energy that can be used practically, the time required for the sweep tends to become longer, and the fluctuations in the ion beam current during that time are no longer negligible.

The present invention has been made in view of the above, and is capable of accurately controlling the implantation concentration to always maintain the target implantation concentration even when there are steep fluctuations in the ion beam current or when it is necessary to implant dopants over a wide range. The purpose is to provide an ion implantation device that can perform ion implantation.

<Means for Solving the Problems> The configuration for achieving the above object will be explained with reference to the basic conceptual diagram shown in FIG. 1. The present invention has an ion source,
an ion beam generating section a comprising an ion accelerating section, etc.;
In an apparatus that has a sweep device C that changes the relative position of the ion beam B from the ion beam generator a and the target b in the X and y directions, and implants ions in two-dimensional directions onto the target b, the ion beam B By means of a beam current measuring means d that measures the beam current moment by moment, and by sequentially storing the beam current measurement results in correspondence with the sweep position of the ion beam B, the actual amount of ions implanted onto the target beam B is x-7. a first storage means e for storing the distribution;
a second storage means f for storing x-7 distribution of the target ion implantation amount onto the target b set in advance;
and a control means g for giving a control signal to the sweep device C based on the comparison result of the data at the corresponding X-y coordinates in the second storage means e and f, respectively, and x-7 distribution of the actual ion implantation amount. It is characterized by the configuration in which the sweep position of the ion beam B is controlled so that the x-7 distribution of the target ion implantation amount becomes equal to the x-7 distribution of the target ion implantation amount.

<Operation> The beam current measuring means d measures the momentary beam current of the output ion beam B, and this measurement result is used as the first
By sequentially storing data in the storage means e corresponding to the sweep position of the ion beam B, the x-7 distribution of the actual ion implantation amount on the target b is stored in the first storage means e. Become. The contents of this first storage means e and the second
By comparing the contents of the storage means f with respect to the corresponding x-y coordinates, the difference between the actual ion implantation amount and the target ion implantation amount at each coordinate point can be obtained.

Ion beam B so that this difference becomes O for each coordinate point.
By controlling the sweep position of , ions can be implanted into target b with a desired concentration distribution.

<Example> Embodiments of the present invention will be described below based on the drawings.

FIG. 2 is a block diagram showing the configuration of an embodiment of the present invention.

The ion beam generating section 1 includes an ion source, a linac, etc., and adds energy to ions from the ion source, and outputs the ions as a pulsed beam. This ion beam is
The light passes through the axis deflection electrodes 2a, 2b and the X-axis deflection electrodes 3a, 3b and enters the target T.

Y-axis and X-axis deflection electrodes 2a, 2b and 3a.

A high voltage power supply 4 for y-axis deflection and a high voltage power supply 5 for X-axis deflection are connected to 3b, respectively, and based on the X-axis signal and the X-axis signal output from the A voltage can be applied to generate an electric field of a magnitude that deflects the ion beam by an arbitrary amount in the y- and x-axis directions.

That is, the ion beam incident position on the target T is
The magnitude of the voltage applied to the y-axis and X-axis deflection electrodes 2a, 2b and 3a, 3b, in other words, the X-axis signal and
Uniquely determined by the value of the axis signal.

On the other hand, the pulsed ion beam from the ion beam generator 1 passes through the pulse transformer 7 at an arbitrary position before being incident on the target T. This pulse transformer 7 is
This is provided to measure the beam current of the ion beam without interfering with the flow of the ion beam.The amplifier 8 amplifies the voltage signal generated when the ion beam passes through the pulse transformer 7, and converts the voltage to the pulse transformer. A converter 9 converts it into a pulse train. As a result, the ion beam generating section 1
Changes in the ion beam current from 1 to 2 are captured as changes in the frequency of the pulse train described above.

The pulse signal from the voltage-pulse converter 9 is sent to the counter 1
It is entered as 0. This counter 10 counts input pulses and supplies the count value to a two-dimensional actual injection amount storage device 11, and also based on the X-axis signal and the X-axis signal from the aforementioned X-axis and y-axis sweep control device 6. will be reset.

The two-dimensional actual injection amount storage device 11 has an address set for each minute region formed by dividing the x-y plane into a mesh shape, and is accessed by the above-mentioned X-axis signal and X-axis signal, and is accessed by the counter 10. Adds the count value immediately before the reset to the contents of the accessed address. That is, in synchronization with the sweep of the ion beam, the ion beam current at each sweep position is measured moment by moment, and the measured data is sequentially added and stored in the corresponding address in the two-dimensional actual implantation dose storage device 11. Become.

Therefore, the contents of the two-dimensional actual implantation amount storage device 11 represent the x-7 distribution of the actual implantation amount of ions implanted into the target so far.

The added data is then output as an actual injection amount signal and supplied to the X-axis and y-axis sweep control device 6.

The two-dimensional target injection amount storage device 12 is for storing the x-7 distribution of the target injection amount to the target T, and corresponds to the two-dimensional actual injection amount storage device 11 described above.
Addresses are set in minute regions formed by dividing the y-plane into mesh shapes, and target injection amounts are stored in advance in each address based on a desired distribution. The contents of this two-dimensional target injection amount storage device 12 similarly include the X-axis signal and
It is read out by the axis signal and x@ as the target injection volume signal.
It is supplied to the y-axis sweep controller 6.

The X-axis and y-axis sweep control device 6 constantly compares the contents of the two-dimensional actual injection amount storage device 11 and the two-dimensional target injection amount storage device 12 at each sweep position, so that the difference between the two becomes 0 at all positions. , the X-axis signal, and the X-axis signal to control the X- and Y-axis sweep speeds and sweep patterns of the ion beam. That is, for example, at a position where a relatively large amount of injection is performed, the sweep speed is increased or thinned out during subsequent sweeps. Thereby, even if there is a change in the ion beam current, the dopant is implanted into the target T in a desired preset pattern and with a desired implantation concentration distribution.

In the above embodiment, an electric field was used to sweep the ion beam, but it is also possible to use a magnetic field, mechanically change the target, or a combination of these. Of course, it is possible.

In addition, in the above embodiments, the ion beam is pulsed and the change in the ion beam current is measured without disturbing the ion flow before the ion beam enters the target using a pulse transformer. If the beam is a direct current as usual, it can be pulsed using a beam chopper or the like and the ion beam current can be similarly measured before it is incident on the target. Furthermore, although real-time performance is hindered, the beam current incident on the target may be measured with an ammeter and the measured data may be sent to a two-dimensional actual implantation dose storage device.

<Effects of the Invention> As explained above, according to the present invention, the beam current of the ion beam is measured moment by moment, the x-7 distribution of the actual ion implantation amount is determined and stored based on the measured values, and the The contents,
The ion beam is compared with the x-7 distribution of the target ion implantation amount set in advance, and sweep control of the ion beam is performed based on the comparison result, so even if there is a steep fluctuation in the ion beam current, it can be adjusted accordingly. Sweep control is executed, and almost no errors occur due to beam fluctuations in the implantation amount.

Furthermore, since the x-7 distribution of the actual implantation amount is controlled to be equal to the Any injection distribution can be realized.

[Brief explanation of the drawing]

FIG. 1 is a basic conceptual diagram showing the configuration of the present invention, and FIG. 2 is a block diagram showing the configuration of an embodiment of the present invention. 1-Ion beam generation unit 2a, 2b-Y-axis deflection electrodes 3a, 3b--X-axis deflection electrode 4--High voltage power supply for y-axis deflection 5--High voltage power supply for x-axis deflection 6-- - x-axis y-axis sweep control device 7 - pulse transformer

Claims (1)

[Claims] It has an ion beam generation section comprising an ion source, an ion acceleration section, etc., and a sweep device that changes the relative position of the ion beam from the ion beam generation section and the target in the x and y directions. In an apparatus for implanting ions in the direction, a beam current measurement means for measuring the beam current of the ion beam moment by moment, and a beam current measurement result sequentially stored in correspondence with the sweep position of the ion beam, are used to implant ions onto the target. a first storage means for storing an x-y distribution of an actual ion implantation amount; a second storage means for storing an x-y distribution of a target ion implantation amount onto a preset target; and a control means for supplying a control signal to the sweep device based on a comparison result of data at corresponding x-y coordinates in the second storage means, so that the x-y distribution of the actual ion implantation amount is An ion implantation apparatus characterized in that the sweep position of an ion beam is controlled so as to be equal to the xy distribution of a target implantation amount.