JPH06119902A - Ion implantation device - Google Patents

Abstract

PURPOSE:To provide an ion implantation device which can enhance the performance of a device and improve the yield by preventing inclusion of any foreign matters such as metal impurities in the device. CONSTITUTION:A liner 14 of silicon is affixed to the inner surface of an ion analyzing magnet 13, and a beam mask 15, gate electrode 16, slit 18, and low energy ion reflecting electrode 19 are installed between the magnet and an accelerator tube 20 in the sequence as named, and the output of a beam gate power supply 17 is impressed on the gate electrode 16 so that an ion beam is hopped up.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion implanter.

[0002]

2. Description of the Related Art A conventional ion implanter includes an ion source A, an ion analyzing magnet B, an accelerating tube C, a Q lens D, and an ion beam in the Y direction (vertical direction) as shown in FIG. It is composed of an ion beam deflection Y electrode E for deflection, an ion beam deflection X electrode F for deflecting the ion beam in the X direction (horizontal direction), and an ion implantation chamber G with a wafer.

In such an ion implantation apparatus, the ions generated in the ion source A are accelerated by the extraction electrode, and then only the ions required for ion implantation are selected by the ion analysis magnet B. Then, after that, the selected ions are accelerated by the accelerating tube C and then converged by the Q lens D so that the ion beam having the optimum beam shape can be injected into the wafer in the ion implantation chamber G. The ion beam converged by the Q lens D is deflected by the ion beam deflecting Y electrode E and the ion beam deflecting X electrode F, and scanned on the wafer in the ion implantation chamber G. In that case, the energy of the ion beam and the number of ions injected into the wafer are determined by the purpose of the device.
The number of ions of the ion beam injected into one wafer is controlled by applying a high DC voltage gate voltage to the ion beam deflecting Y electrode E at a high speed or not applying it. That is, when the number of ions of the ion beam injected into one wafer reaches a predetermined number, a gate voltage is applied and the injection of the ion beam into the wafer is stopped. However, when the application of the gate voltage is released, the ion beam is injected into the wafer.

[0004]

In the conventional ion implantation apparatus, when the number of ions of the ion beam implanted into one wafer reaches a predetermined number as described above, the DC high voltage is applied to the ion beam deflection Y electrode E. A gate voltage of a voltage is applied to stop the ion beam injection into the wafer. The reason why the ion beam injection to the wafer is stopped is that the ion beam is repelled by applying a gate voltage to the ion beam deflecting Y electrode E and hits the inner wall of the vacuum container without reaching the wafer. When the ion beam hits the inner wall of the vacuum container, the inner wall of the vacuum container is sputtered, and the particles of the inner wall material of the vacuum container are scattered in the vacuum container. Therefore, some of the particles of the inner wall material of the scattered vacuum container adhere to the wafer. As a result, foreign matters such as metal impurities are mixed into the device formed from the wafer, which causes a problem that the device performance is deteriorated.

An object of the present invention is to solve the above-mentioned problems of the prior art, prevent foreign substances such as metal impurities from being mixed into the device, improve the performance of the device, and improve the yield. An injection device is provided.

[0006]

In order to achieve the above object, the present invention is directed to selecting an ion required for ion implantation from an ion beam extracted from an ion source by an ion analysis magnet, and then selecting an ion. In an ion implanter for accelerating a beam with an accelerating tube and injecting it into a wafer, a silicon liner is attached to the inner surface of the ion analyzing magnet, and a beam mask is provided between the ion analyzing magnet and the accelerating tube. , A gate electrode, a slit, and a low-energy ion reflection electrode are arranged in this order, and an output from a beam gate power source is applied to the gate electrode to jump up the ion beam.

[0007]

In the present invention, when only the ions necessary for ion implantation are selected by the ion analysis magnet, a part of the ion beam is sputtered on the silicon liner attached to the inner surface of the ion analysis magnet 13. However, the ions generated by the sputtering are reflected by the electric field formed between the slit and the low energy ion reflection electrode and do not reach the acceleration tube. The ion beam selected by the ion analysis magnet passes through the beam mask and reaches the gate electrode. When the output from the beam gate power supply is applied to the gate electrode, the ion beam is flipped up. The ion beam that has been flipped up passes through or collides with the slit. The ion beam that has passed through the slit passes through the low energy ion reflection electrode and reaches the acceleration tube.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. The ion implantation apparatus according to the first embodiment of the present invention is shown in FIGS. 1 and 2, and in FIG.
An ion extraction power source 12 is connected to the ion source 11, and the ions generated in the ion source 11 are extracted as a beam by the output thereof. The extracted ion beam passes through the ion analysis magnet 13, in which case only the ions necessary for ion implantation are selected. A liner 14 made of silicon is attached to the inner surface of the ion analysis magnet 13. Ion analysis magnet 1
A beam mask 15 made of silicon having an ion beam passage hole is arranged in the exit side direction of 3, and the beam mask 15 prevents the ion beam from hitting a gate electrode 16 described later. A gate electrode 16 for flipping up the ion beam is arranged behind the beam mask 15, and a beam gate power supply 17 is connected to the gate electrode 16. When the number of ions to be injected into the wafer, which will be described later, reaches a required value, the beam gate power supply 17 is supplied with a signal from a dose measuring device (not shown) for measuring the number of ions, and then from the beam gate power supply 17 Is applied to the gate electrode 16. A slit 18 made of silicon is arranged behind the gate electrode 16, and further behind the slit 18, the ion source 11 is provided.
A low energy ion reflection electrode 1 for applying a high voltage that is about 10 KV lower than the extraction voltage for extracting the ion beam.
9 is arranged, and an electric field is formed between the slit 18 and the low energy ion reflection electrode 19. An acceleration tube 20 is arranged behind the low energy ion reflection electrode 19. Although not shown in the figure, a Q lens, an ion beam deflecting Y electrode for deflecting the ion beam in the Y direction (vertical direction), and an ion beam in the X direction (horizontal direction) are provided behind the accelerating tube 20, as in the conventional case. These are arranged in the order of the ion beam deflection X electrode to be deflected and the ion implantation chamber in which the wafer is present.

In the above-described first embodiment, the ions generated in the ion source 11 are extracted as an ion beam by the output of the ion extraction power source 12. The extracted ion beam passes through the ion analysis magnet 13, but only the ions necessary for ion implantation are selected there. A part of the ion beam passing through the ion analysis magnet 13 sputters the silicon liner 14 attached to the inner surface of the ion analysis magnet 13. The ion beam that has passed through the ion analysis magnet 13 has a beam mask 15, a gate electrode 16, and a slit 1.
8, passing through the low energy ion reflection electrode 19 in this order,
It reaches the acceleration tube 20. When passing, the beam mask 15 plays a role of preventing the ion beam from hitting the gate electrode 16. Further, the electric field formed between the slit 18 and the low-energy ion reflection electrode 19 reflects ions that cause contamination, which are generated by sputtering the silicon liner 14 or the like, and the ions do not reach the acceleration tube 20. I am trying. After being accelerated there, the ion beam reaching the accelerating tube 20 passes through the Q lens and the ion beam deflecting Y electrode, is bent by the ion beam deflecting X electrode, and is injected into the wafer in the ion implantation chamber as in the conventional case.

Between the ion analysis magnet 13 and the ion beam deflecting X electrode, some of the ions capture electrons and become neutral particles. The neutral particles go straight without being bent by the ion beam deflecting X electrode and sputter the inner wall of the vacuum container. In order to prevent the generation of foreign matters such as metal impurities due to this sputtering, a silicon liner is attached to the portion irradiated with the neutral particles. Further, the graphite material that has been conventionally used to prevent the generation of foreign matters such as metal impurities is replaced with silicon material. For example, a mask in an ion implanter.

In the embodiment, when the number of ions to be injected into the wafer reaches a required value, a signal from a dose measuring instrument (not shown) for measuring the number of ions is sent to the beam gate power source 17 as a signal.
Then, the output from the beam gate power supply 17 is applied to the gate electrode 16. As a result, the ion beam is flipped up by the gate electrode 16, does not pass through the slit 18, and the ion implantation into the wafer is stopped. At the same time, when the output from the beam gate power supply 17 is applied to the gate electrode 16, a signal is also sent to the ion extraction power supply 12 and the extraction of the ion beam from the ion source 11 is also stopped. Then, after exchanging the wafer, the ion extraction power source 12 is turned on, and then the application to the gate electrode 16 is released, so that the ion beam is again injected into the wafer.

By the way, FIG. 3 shows a second embodiment of the present invention. In FIG. 3, the central axis of the gate electrode 16 and the central axes of the slit 18, the low energy ion reflection electrode 19 and the accelerating tube 20 are shown. It forms a sharp angle. Therefore, unlike the first embodiment, when the output from the beam gate power supply 17 is applied to the gate electrode 16 and the ion beam is jumped up from the gate electrode 16, the ion beam passes through the slit 18. Ion implantation was performed on the wafer, and conversely, beam gate power supply 1
When the output from 7 is not applied to the gate electrode 16 and the ion beam is not repelled from the gate electrode 16, the ion beam hits the slit 18 and the ion implantation into the wafer is stopped. Such an operation is the reverse of that of the first embodiment. The reason for doing the opposite is that, in the case of the first embodiment, when the beam gate power supply 17 fails, the ion beam cannot be jumped up from the gate electrode 16 and the problem that the ion implantation into the wafer cannot be stopped occurs.
This is because this problem is solved in the second embodiment, and when the beam gate power supply 17 fails, it is possible to stop the ion implantation into the wafer.

Instead of sticking the silicon liner 14 on the inner surface of the ion analysis magnet 13, the vacuum container of the ion analysis magnet 13 may be made of a silicon block. Further, a conventional method of reducing foreign matters such as metal impurities by incorporating a vacuum pump in the gate electrode portion can be added.

[0014]

According to the present invention, the ions generated by sputtering the silicon liner attached to the inner surface of the ion analysis magnet are reflected by the electric field formed between the slit and the low energy ion reflection electrode, If the output from the beam gate power supply is applied to the gate electrode without reaching the accelerating tube, the ion beam bounces up, and the ion beam passes through the slit or collides with it, so that foreign substances such as metal impurities are caught in the device. The contamination is prevented, the performance of the device is improved, and the yield is improved. Further, since the gate electrode is arranged in front of the accelerating tube, the ion beam to be repelled has low energy. Therefore, the gate electrode can be downsized, and the output from the beam gate power supply applied to the gate electrode can be reduced. Furthermore, since the silicon liner is attached to the inner surface of the ion analysis magnet, the release of gas from the inner surface of the ion analysis magnet is suppressed. As a result, the probability that the divalent positive ions such as boron, phosphorus and arsenic collide with the residual gas in the ion analysis magnet is reduced, and the beam current of the divalent positive ions such as boron, phosphorus and arsenic is increased.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an ion implantation apparatus of a first embodiment of the present invention.

FIG. 2 is an explanatory view showing a part of a main part of the first embodiment of the present invention.

FIG. 3 is an explanatory view showing a part of a main part of a second embodiment of the present invention.

FIG. 4 is an explanatory view showing a conventional ion implanter.

[Explanation of symbols]

 11-Ion source 12-Ion extraction power supply 13-Ion analysis magnet 14-Liner 15-Beam mask 16-・ ・ ・ Gate electrode 17 ・ ・ ・ ・ ・ Beam gate power supply 18 ・ ・ ・ ・ ・ Slit 19 ・ ・ ・ ・ Low energy ion reflection electrode 20 ・ ・ ・ ・ Acceleration tube

Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical indication location H01L 21/265 (72) Inventor Osamu Tsukoshi 2500 Hagien, Chigasaki City, Kanagawa Japan Vacuum Technology Co., Ltd

Claims (1)

[Claims] 1. Ions for implanting only ions necessary for ion implantation from an ion beam extracted from an ion source with an ion analysis magnet, accelerating the ion beam with an accelerating tube, and implanting it into a wafer. In the implanter, a liner made of silicon is attached to the inner surface of the ion analysis magnet, and between the ion analysis magnet and the acceleration tube, a beam mask, a gate electrode, a slit, and a low energy ion reflection electrode are arranged in this order. An ion implanter characterized by applying an output from a beam gate power supply to the gate electrode to bounce up an ion beam.