JPH025345A - Ion implantation - Google Patents

Abstract

PURPOSE:To cope with different manufacturing processes by switching the type of ion beam scanning irradiation process between horizontal and sectorial shapes. CONSTITUTION:An ion beam 21 which has passed through a primary electrostatic deflection system 24 is collimated with a 1st ground mask 27, passes through a 2nd electron restriction electrode 28, and enters a secondary electrostatic deflection system 31 comprising a vertical deflection plate 29 and a horizontal deflection plate 30. The beam is made into a vertically parallel beam 21a as an oppositely biased voltage synchrous with that of a scanning plate 22 is applied to the deflection plate 29, enters the deflection plate 30, made similarly into a horizontally parallel beam 21b, passes through a parallel beam measurement mechanism 32 and a 2nd ground mask 33, and is irradiated to a semiconductor wafer 35 on a platen 34. When processes except for the ion implantation are set to process the wafer by sectorial scanning irradiation, the operation of the deflection system 31 is stopped and switched to the sectorial scanning irradiation. Thus, different manufacturing processes can be coped with.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to an ion implantation method.

(Prior Art) In general, ion implantation technology is widely used as a technology for doping an object to be processed, such as a silicon or gallium arsenide substrate, with impurities.

As an ion implanter used for such ion implantation,
For example, in a medium current type ion implanter, as shown in FIG. 4, an ion beam 4 output from an ion beam generator 3 consisting of an ion generator 1, a mass analysis magnet 2, etc. is accelerated by an accelerator 5, After being shaped into a predetermined beam by the quadrupole electrostatic lens 6, it is scanned in the x-y direction by the action of the electric field of the vertical scanning plate 7 and the horizontal scanning plate 8, collimated by the ground mask 9, and sent to the platen 10.
It is configured to irradiate an object to be processed, such as a semiconductor wafer 11, placed above.

(Problem to be solved by the invention) Only 1. Therefore, in the conventional ion implantation method described above,
Since the scanning beam irradiation is carried out in a fan-like scanning manner, a problem arises in that the beam incidence angle differs depending on the part of the substrate to be ion-implanted, making it impossible to perform uniform ion implantation work. For example, the beam incidence angle differs between the central part and the peripheral part of the semiconductor wafer to which the ion beam is irradiated, making it impossible to perform uniform ion implantation over the entire surface of the semiconductor wafer.

Conventionally, it has been proposed to solve the above non-uniformity problem by performing parallel irradiation scanning (hereinafter referred to as parallel scanning) of the ion beam, but this method increases the size of the equipment and significantly increases manufacturing costs. There were problems such as an increase in the amount.

Furthermore, in the conventional parallel scanning method, the scanning method is fixed, so when it is desired to process a workpiece using the fan-like scanning method due to the manufacturing process, the scanning method cannot be switched, and it is difficult to switch between various manufacturing processes. There was also the problem of not being able to respond flexibly.

The present invention has been made to solve the above-mentioned problems, and has a simple structure that realizes parallel scanning of ion beams, greatly improves uniformity in ion implantation work, and furthermore, parallel scans. The purpose is to provide an ion implantation method that can be flexibly adapted to various manufacturing processes by making it possible to switch between the scanning method and the fan scanning method.

[Means of the Invention (Means for Solving the Problems)] The ion implantation method of the present invention scans an ion beam in the horizontal and vertical directions with a first electrostatic deflection system, and scans an ion beam in the horizontal and vertical directions with a first electrostatic deflection system. In a beam scanning method of an ion implantation apparatus that converts the ion beam into a parallel beam and irradiates the object to be processed in parallel scanning, the operation of at least the second electrostatic deflection system is controlled based on the desired processing content. According to this method, the ion beam is scanned and irradiated by selecting fan-shaped scanning or parallel scanning.

(Function) The present invention provides at least a second electrostatic charge according to the processing content.
By performing similar operation control, the ion beam can be processed by switching from parallel scanning irradiation method to fan scanning irradiation method, which greatly improves the uniformity of ion implantation work and allows flexible support for various manufacturing processes. becomes possible.

(Example) Hereinafter, an example in which the method of the present invention is applied to a medium current type ion implantation device will be described with reference to the drawings. still,
FIG. 1(a) shows a plan view of the embodiment, and FIG. 1(b) shows a side view thereof.

An ion beam output from an ion source (not shown) is shaped into a desired ion beam 21 by an analysis magnet, an accelerator tube, an electrostatic lens, etc. (not shown), and is shaped into a desired ion beam 21 in the vertical direction (hereinafter referred to as the y direction). The scanning plate 22 and the horizontal direction (
(hereinafter referred to as the X direction)
The light then enters the electrostatic deflection system 24.

Each scanning electrode 22.23 of the primary electrostatic deflection system 24
As shown in the figure, it is connected to a system controller 42 controlled by a device CPU 41, and this device CPU
according to a predetermined program of the system controller 4.
2 applies a voltage based on a scanning signal of a predetermined period to the X-direction scanning plate 22 and the X-direction scanning plate 23.

The system controller 42 controls the operation of the entire electrostatic deflection system, such as creating a scanning signal and switching signals, based on processing information programmed into the device cPU 41.

In this embodiment, as a scanning signal, one signal is sent to the X direction scanning plate 22.
17. 1911z, a triangular wave of 1019 Hz is used in the x-direction scanning plate, and the incident ion beam 21 is deflected in a predetermined direction by the change in the electric field between each electrode at this time, and scanning irradiation of the beam is performed.

Further, in the X-direction scanning plate 23, the applied voltage is controlled so that the ion beam 21 is bent at an offset angle θ, for example, 7″ with respect to the beam traveling axis, and neutral ions mixed in the ion beam 21 are Miscellaneous ions such as ions are sorted out at this beam bending portion and fly in a direction different from the desired ions, for example, in a straight direction 25.

The miscellaneous ions selected above, such as neutral ions, are
The neutral ions collide with a shield 26 made of carbon, for example, arranged in the flight direction 25, and are prevented from entering the object to be processed.

In this way, the ion beam that has passed through the primary electrostatic deflection system 24 is collimated by the first ground mask 27, passes through the secondary electron suppression electrode 28, and then passes through the X-direction deflection plate 29 and the X-direction deflection plate 30. The beam enters a secondary electrostatic deflection system 31 consisting of:

A reverse bias voltage is applied to the X-direction deflection plate 29 almost in synchronization with the X-direction scanning plate 22, and the incident ion beam 21 is repelled toward the center between the electrodes of the X-direction deflection plate 29. The beam is made parallel to the X direction.

The ion beam 21 a that has been made into a parallel beam in the X direction by the X direction deflection plate 29 enters the X direction deflection plate 30 . A reverse bias voltage is also applied to the X-direction deflection plate 30 in almost synchronization with the X-direction scanning plate 23, and the same principle as that of the X-direction deflection plate 29 is used to convert the beam into a parallel beam in the X-direction. be done.

The ion beam that has passed through the secondary electrostatic deflection system 31 in this way becomes an ion beam 21b that is parallel to the X-X direction, and passes through the parallel beam measurement mechanism 32 and the second ground mask 33. , an object to be processed, such as a semiconductor wafer 35, placed on a platen 34 is scanned and irradiated. The semiconductor wafer 35 is tilted at a tilt angle of, for example, about 7'' with respect to the beam irradiation axis for the purpose of preventing channeling.

Incidentally, a ground electrode 36 is arranged on the ion beam irradiation axis so as to sandwich each deflection plate 29, 30 of the secondary electrostatic deflection system.
．． 37 and 38 are for preventing disturbance of the electric field at the ends of each deflection plate 29 and 30.

By converting the ion beam electrostatically scanned in the x-x direction in this way into parallel beams in the x-x directions by the secondary electrostatic deflection system 31, parallel beams can be easily created. Uniform ion implantation processing of the semiconductor wafer 35 can be performed.

Incidentally, the manufacturing process for processing objects such as semiconductor wafers consists of a combination of many manufacturing steps, and manufacturing steps other than the ion implantation step are similar to processing semiconductor wafers implanted with ions by conventional fan-shaped scanning irradiation. If the equipment, equipment, etc. are set up, there may be cases where the semiconductor wafer must be processed using the conventional fan-shaped scanning irradiation method even in the ion implantation process.

In such a case, by stopping the operation of the secondary electrostatic deflection system 31 described above, it is possible to switch to conventional fan-shaped scanning irradiation.

At the time of switching, information on the object to be processed and its scanning method is stored in advance in the storage section of the device CPU 41 or the system controller 42, so that processing can be automatically performed using the desired scanning method. Of course, a manual switching mechanism may be provided to manually switch.

Further, during the fan-shaped scan irradiation, as shown in FIG. The scanning signal of the primary electrostatic deflection system 24 is set to be corrected so that the scanning angle θ2 of the scanning plate 22 is smaller than the scanning angle θ1 during parallel scanning.

The scanning signal may be modified, for example, by using a signal that reduces the voltage applied to the electrodes.

By performing scanning at a narrower scanning angle than conventional fan-shaped scanning (hereinafter referred to as narrow scanning),
Since the difference in the beam incidence angle depending on the part of the semiconductor wafer 35 is reduced, the uniformity of processing is improved, and since it is possible to use a manufacturing process compatible with the conventional fan scanning method, it is possible to change the manufacturing process etc. Necessary expenses can be reduced and increases in manufacturing costs can also be prevented.

[Effects of the Invention] As explained above, according to the ion implantation method of the present invention, although it is a simple method, it is possible to perform parallel scanning of the ion beam, and furthermore, it is possible to perform parallel scanning of the ion beam depending on the processing content. Since it is possible to switch to the narrow scan method, it is possible to flexibly respond to various manufacturing processes.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an embodiment of the present invention.
) is a plan view of the embodiment, FIG. 1(b) is a side view thereof, and FIG.
The figure shows the control system of each electrostatic deflection system in the embodiment, Figure 3 is a diagram to explain the switching operation between parallel scan method and narrow scan method, and Figure 4 is a conventional medium current type ion implanter. FIG. 21...Ion beam, 22...Y direction scanning number, 23...X direction scanning plate, 24...
... Primary electrostatic deflection system, 26 ... Neutral beam shield, 29 ... X direction deflection plate, 30
......X direction deflection plate, 31...Second electrostatic deflection system, 34...Platen, 35...
Semiconductor wafer, 41...Device CPU, 42...
...System controller.

Claims (1)

[Claims] In an ion implantation method in which an ion beam is scanned in horizontal and vertical directions by a first electrostatic deflection system, the ion beam is converted into a parallel beam by a second electrostatic deflection system, and the object to be processed is irradiated with parallel scanning, An ion implantation method characterized by controlling the operation of at least the second electrostatic deflection system based on desired processing contents, and selectively performing scanning irradiation with the ion beam by selecting fan-shaped scanning or parallel scanning.