JPS63124354A - Ion beam device - Google Patents

Abstract

PURPOSE:To make it possible to maintain a desirable value of an ion beam current by disposing a variable slit for ion beam current control and controlling its opening amount in accordance with the ion beam current for a material to be irradiated with the ion beams. CONSTITUTION:When beams of specific species of ions 2B attain to a Faraday cup 8, an ion beam current is measured by a measuring device 9 and its value is applied to a one-sided terminal of a differential amplifier 11. The amplifier 11 is controlled and outputted so that its input value is identical with a set value of a setting device 12 and its output signal is applied to a relay 13. The relay 13 is operated in accordance with the controlling output so that a switch 14 is closed either on a positive electrode power source side 15 or on a negative electrode power source side 16. This switching operation allows a driving device 6 to increase or decrease the opening amount of the variable slit 5. Because the beam transmitting amount of ions 2B increases or decreases as the opening amount of the slit 5 increases or decreases, respectively, a current value of prescribed species of ion beams passing through the slit 5 and advancing to a wafer 7 can be modified and regulated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to ion beam technology, and in particular to technology for controlling the irradiation amount of an ion beam. Concerning effective techniques that can be used to type.

[Conventional technology]

In the manufacturing process of semiconductor devices, as an ion implanter that implants ions of impurity elements into wafers, in order to maintain the beam current of implanted ions at a desired value, the total amount of ions emitted is changed by controlling the capacity of the ion source. Some are configured to adjust, and some are configured to vary and adjust the amount of emitted ions passing through by placing a variable slit just downstream of the ion source.

An example of the ion implantation technology described is "Electronic Materials November 1981 Special Edition" published by Kogyo Research Association Co., Ltd., November 10, 1981, pages 90 to 94.

[Problem that the invention seeks to solve]

However, in ion implantation equipment that controls the capacity of the ion source, when the amount of ions ejected is reduced, the beam current becomes unstable due to the discharge stopping inside the ion source and fluctuations in plasma density. In addition, in an ion implantation device that uses a variable slit to limit the amount of ion beam passing through, the ion beam emitted from the ion source contains miscellaneous ion species, so the amount of implanted ions must be kept constant. The inventors have discovered that there is a problem in that it is difficult to

An object of the present invention is to provide an ion beam technique that can maintain the ion beam current at a desired value.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Means for solving problems]

An overview of typical inventions disclosed in this application is as follows.

That is, a variable slit for controlling the ion beam current was provided downstream of the mass spectrometer, and the aperture of this slit was controlled by a controller based on the ion beam current in the object to be irradiated with the ion beam. It is something.

[Effect]

According to the above-described means, since the variable slit is disposed behind the mass spectrometer, the beam current value of the desired ion species itself selected by the mass spectrometer is directly controlled. Therefore, by restricting the ion beam emitted from the ion source and containing miscellaneous ion species using a variable slit, the control accuracy is much better than when attempting to indirectly control the beam current value of the desired ion species. become.

Furthermore, since the ion source can be maintained at its optimum operating value, the occurrence of discharge stoppage and plasma density fluctuation phenomena inside the ion source can be avoided.

Moreover, since the opening amount of the beam current control variable slit is feedbank controlled based on the current beam current value of the object to be irradiated with the ion beam, the control accuracy for the desired value of the ion beam current is extremely good.

〔Example〕

FIG. 1 is a schematic diagram showing an ion implantation apparatus according to an embodiment of the present invention.

In this embodiment, the ion implantation apparatus is equipped with an ion source 1, which generates ions of an impurity element to be implanted into the wafer, extracts the generated ions, and emits them in the form of a beam. It is configured. A mass analysis magnet 3 made of a fan-shaped electromagnet or the like is disposed downstream of the ion source 1, and this mass analysis magnet 3 has a mass dispersion effect on the deflection plane as well as a lens effect to converge the beam. The two diverging beams from the ion source 1 are focused on a fixed point determined by the dimensions of the electromagnet. A mass spectrometry slit 4 is disposed downstream of the magnet 3 so as to approximately coincide with the fixed convergence point, and the magnet 3 and slit 4 allow the ions to be selected from among the various miscellaneous ions emitted from the ion source 1. A mass spectrometer that selects different ion species is substantially configured.

A variable slit 5 for beam current control is arranged downstream of the mass spectrometry slit 4 so that the beam current value of the ions 2B selected by the mass spectrometry slit 4 can be controlled by the opening amount of the variable slit 5. 5 is configured such that its opening amount can be changed and adjusted by a drive device 6.

This variable slit driving device 6 is configured to be controlled by a controller to be described later.

A Faraday cup 8 is arranged downstream of the variable slit 5 and is configured to hold a wafer 7 as an object to be irradiated with the ion beam. The structure is such that the beam of ions 2B is uniformly irradiated. An ion beam current measuring device 9 is installed on the wafer 7 in the Faraday cup 8.
The measuring device 9 is connected to the controller 10 so as to be able to input the measurement results to the controller 10.

The controller 10 includes a differential amplifier 11, and a pair of input terminals of the amplifier 11 include the ion beam current measuring device 9, a variable voltage source, etc., and a setting for setting a desired ion beam current/value. 12 are connected to each other. On the other hand, a relay 13 is connected to the output terminal of the amplifier 11, and the relay 13 is connected to the drive device 6.
The switch 14 is configured to control a switch 14 connected to the switch 14 . A positive polarity power source 15 and a negative polarity power source 16 are respectively connected to the switch 14, and the switch 14 closes both types of power sources 15 or 16 to turn on the drive device 6.
It is configured to perform control to increase or decrease the opening amount of the variable slit 5.

Next, the action will be explained.

The beam of ions 2A emitted from the ion source 1 is deflected by the mass analysis magnet 3, and only desired ion species pass through the gap of the mass analysis slit 4 as a beam of ions 2B of a specific species. The beam of ions 2B of a specific type is controlled by the variable slit 5 as described later, and then irradiated onto the wafer 7 held in the Faraday cup 8 and driven into the wafer 7.

By the way, since the amount of impurity elements implanted into the wafer greatly affects the performance of semiconductor devices, the beam current value of the specific type of ion 2B implanted into the wafer, which defines the implantation amount, is determined to be different from the set value. It is desirable that it be maintained constant from the start until the completion of a given drive.

Therefore, in this embodiment, a variable slit 5 is provided behind the mass analysis slit 4, so that the current value of the specific type of ion beam implanted into the wafer 7 is maintained at the set value.

That is, when the beam of ions 2B of a specific type reaches the Faraday cup 8, the measuring device 9 measures the ion beam current and transmits the value to the differential amplifier 1 in the controller 10.
1 to one input terminal. Differential amplifier 11 applies an output to relay 13 to control this input value to be equal to the set value from setter 12 . Relay 13 switches switch 14 to positive or negative polarity power supply 1 according to its control output.
Operate so that the 5 or 16 side is closed. By operating this switch, the drive device 6 increases or decreases the opening amount of the variable slit 5. When the opening amount of the variable slit 5 increases or decreases, the amount of the ion beam 2B passing through increases or decreases, so that the wafer 7 passes through the variable slit 5.
The ion beam current value for a given species to reach will be modified and adjusted.

Thereafter, by repeating the above operation, the specific type of ion beam current value to be implanted into the wafer 7 is determined by the setting device 1.
2 is controlled to maintain the preset value at all times.

According to the embodiment described above, the following effects can be obtained.

(1) By arranging a variable slit for controlling the ion beam current downstream of the mass spectrometer, and configuring the opening amount of this slit to be controlled by a controller based on the ion beam current in the Faraday cup, Since the ion beam irradiation amount can be controlled to remain constant with respect to a desired set value, the accuracy of the ion beam irradiation amount relative to the desired value can be improved.

(2) By increasing the precision of the total amount of ion beam irradiation, the amount of ion implantation can be precisely controlled, thereby improving the quality and reliability of the semiconductor device.

(3) By arranging the variable slit downstream of the mass spectrometer, the beam current value of the desired ion species itself after being selected by the mass spectrometer can be directly controlled. Control accuracy can be greatly improved compared to the case where the emitted beam containing various miscellaneous ion species is limited by a variable slit and the beam current value for a desired ion species is indirectly controlled.

(4) By controlling the ion beam after the mass spectrometer, it is possible to maintain the ion source at its optimum value, thereby avoiding the occurrence of discharge stoppage and plasma density fluctuation phenomena inside the ion source. can do.

(5) According to (4) above, the incoming current type device can be used for the area of the medium-sized flow type device, so that equipment investment can be reduced.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. Nor.

For example, a controller for feedback controlling the variable slit is not limited to being configured to perform control using analog signals, but may be configured to perform control using digital signals.

The above explanation has mainly been about the application of the invention made by the present inventor to ion implantation technology, which is the background field of application. The present invention can be applied to general ion beam devices such as ion beam exposure devices, ion beam exposure devices, and the like. The present invention exhibits excellent effects when applied at least to the case of controlling the irradiation amount of an ion beam.

〔Effect of the invention〕

A brief explanation of the effects obtained by typical inventions disclosed in this application is as follows.

By disposing a variable slit for controlling the ion beam current downstream of the mass spectrometer, and configuring the slit so that its aperture is controlled by a controller based on the ion beam current in the object to be irradiated with the ion beam, Since the ion beam irradiation amount can be controlled to remain constant with respect to a desired set value, the accuracy of the ion beam irradiation amount relative to the desired value can be improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an ion implantation apparatus according to an embodiment of the present invention. ■...Ion source, 2A, 2B...Ion, 3...
Mass spectrometry magnet, 4...Mass spectrometry slit, 5.
... Variable slit for ion beam current control, 6... Drive device, 7... Wafer (object to be irradiated with ion beam), 8
... Farade cup, 9 ... Ion beam current measurement device, 10 ... Controller, 11 ... Differential amplifier, 12 ... Desired current value setter, 13 ... Relay, 1
4...Switch, 15.16...Power supply. -I/r〉Yo13 First Sand - Uyuha (Bullet Fang〉Hi゛'1 Begogumi ↑y Nasu)-〉〉Trolla

Claims (1)

[Claims] 1. A mass spectrometer for mass spectrometry of desired ion species in the ion beam emitted from the ion source, and a variable slit for controlling the ion beam current disposed downstream of the mass spectrometer. and a controller that controls the opening amount of the variable slit based on the ion beam current in the object to be irradiated with the ion beam. 2. Claim 1, characterized in that the controller is configured to control the opening amount of the variable slit so that the ion current value in the object to be irradiated with the ion beam becomes a preset value. The ion beam device described.