JPH05205690A - Ion implantation device - Google Patents

Abstract

PURPOSE:To provide an ion implantation device with less risk of contamination. CONSTITUTION:A wafer 2 is held and irradiated with ion beam 3. Of that region of the holding part which is irradiated with the ion beam, at least the exposed area other than wafer is mostly enclosed with a plate 4 of molybdenum, etc. According to this constitution, the substance to be sputtered with ion beam 3 is molybdenum. Molybdenum is easy to be oxidated, and its oxide has volatility and water solubility, and eventual attachment to the wafer surface, chamber, etc., is easily removable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion implanter, and more particularly to an implanter capable of preventing wafer contamination during ion implantation.

[0002]

2. Description of the Related Art FIG. 2 (a) is a diagram showing an outline of the vicinity of a wafer holding part of a conventional typical high current ion implanter, and FIG. 2 (b) shows a part of the wafer holding part. It is a figure which shows the case seen from a beam direction.

As shown in FIGS. 2A and 2B, a plurality of wafers 2 are held on the disk 1 along the edges thereof. The ion beam 3 is irradiated onto the main surface of the wafer 1 from a direction perpendicular to the main surface. And disk 1
Is rotated, ions are implanted into all of the plurality of wafers 2.

In the conventional implanter, the disk 1 is made of aluminum (Al). Ion beam 3 is a way
The surface of the disc 1 as well as the claw 2 is irradiated. At this time, there is a problem that the surface of the disk 1 is sputtered by the ion beam 3 and the wafer 2 is contaminated with aluminum.

Further, a mixture of an oxide of aluminum and an oxide of arsenic, phosphorus or the like adheres to a chamber (not shown) which covers the disk 2 or the like and becomes dirty. This stain is liable to be charged up, and there is a problem that the potential distribution in the faraday is changed.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object thereof is to provide an ion implantation apparatus with less contamination.

[0007]

An ion implantation apparatus according to the present invention comprises a holder for holding a wafer and an irradiator for irradiating the wafer held by the holder with an ion beam. In the ion implantation apparatus described above, at least the exposed surface of the holding portion other than the wafer in the area irradiated with the ion beam is almost covered with any one of molybdenum, tungsten, a molybdenum compound, and a tungsten compound.

[0008]

In the implanting apparatus as described above, at least the wafer in the area of the holding portion irradiated with the ion beam is used.
By substantially covering the exposed surface other than C with any of molybdenum, tungsten, a molybdenum compound, or a tungsten compound, the material of the holding portion sputtered by the ion beam becomes molybdenum, tungsten, a molybdenum compound, or a tungsten compound. .. Molybdenum and tungsten are easily oxidized, and since these oxides have volatility and water solubility, they can be easily removed even if they adhere to the surface of the wafer or the surface of the chamber.
Moreover, even if molybdenum or the like adheres to the Faraday,
It can be easily removed by plasma etching (dry cleaning) with a fluorine-based gas.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to the accompanying drawings.

FIG. 1 (a) is a diagram showing the outline of the vicinity of a wafer holding portion of a high current ion implanter according to an embodiment of the present invention, and FIG. 1 (b) is a part of the wafer holding portion. FIG. 5 is a diagram showing a case where is viewed from the beam direction.

As shown in FIGS. 1A and 1B, a molybdenum (Mo) layer having a thickness of 2 m is formed on a region of the disc 1 made of aluminum, for example, which is irradiated with the ion beam 3.
The plate 5 of m is fixed by screwing, for example. The clamp 5 that holds the wafer 2 is also made of molybdenum.

According to the above-described ion implantation apparatus, at least the exposed surface other than the wafer in the region of the disk 1 irradiated with the ion beam 3 is made of molybdenum. Therefore, the substance sputtered by the ion beam 3 becomes molybdenum. This molybdenum is easily oxidized, and the oxide of molybdenum is volatile and water-soluble, and even if it adheres to the surface of a wafer or the surface of a chamber, it is easily removed from aluminum. be able to. Next, the effect of the above-described embodiment will be described.

With the conventional injection device, the dose amount is 5 × 10 ¹⁵ cm ^-2
When arsenic is driven in, it is about 1 × from the surface of the wafer 2.
Although 10 ¹³ cm ^-2 of aluminum was detected, it was below the detection limit in the device described in the above one example. Also,
For molybdenum, after washing the wafer with water, 1 × 10 ¹⁰
Only cm ^-2 was detected.

The present invention also provides the wafer 2 as described above.
Other than the holding part, the place where the ion beam 3 is irradiated,
For example, by coating the slits and the inner wall of the analyzer magnet with molybdenum, contamination can be reduced in the same manner as above.

In the above embodiment, molybdenum was selected as the material for the plate 4 and the clamp 5, but materials other than molybdenum,
For example, molybdenum-silicide (MoSi ₂ ), dungsten (W), tungsten-silicide (WS)
i ₂ ), a compound of tungsten and molybdenum (Mo
It is also possible to use alloys such as W). Even if these materials are used, it is possible to obtain the same effect as that of the above-mentioned embodiment. Furthermore, since molybdenum-silicide is lighter than molybdenum, it is suitable for mounting on the disk 1 rotating at high speed.

For dry cleaning of the chamber, it is optimal to use oxygen (O ₂ ) plasma or a fluorine-based gas for molybdenum, etc., because the cleaning effect is high.

The present invention can be variously modified without departing from the gist thereof. For example, in the above-mentioned one embodiment, the high current ion implanter using the disk 1 has been described as an example. However, even in the medium current ion implanter which does not use the disk, an ion beam such as a wafer holder is irradiated. Mo, MoSi ₂ , W, WS on the area
By coating with i ₂ , MoW or the like, the same effect as in the above-mentioned embodiment can be obtained.

The entire disk 1 is made of Mo, MoSi.
It is also possible to use ₂ , W, WSi ₂ , MoW, or divide the plate 4 into several segments to reduce the weight thereof.

[0019]

As described above, according to the present invention, it is possible to provide an ion implantation apparatus with less contamination.

[Brief description of drawings]

1A and 1B are views showing an ion implantation apparatus according to an embodiment of the present invention, FIG. 1A is a schematic view of the vicinity of a wafer holding portion, and FIG. 1B is a view of a wafer holding portion. It is a figure which shows the case where a part is seen from the beam direction.

FIG. 2 is a view showing a conventional ion implanter,
(A) is a figure which shows the outline | summary of a wafer holding part vicinity, (b) is a figure which shows a case where a part of wafer holding part is seen from a beam direction.

[Explanation of symbols]

1 ... Disc, 2 ... Wafer, 3 ... Ion beam, 4 ...
Molybdenum plate, 5 ... Molybdenum clamp.

Claims (1)

[Claims] 1. A holding unit for holding a wafer, and an irradiation unit for irradiating the wafer held by the holding unit with an ion beam, wherein the ion beam of the holding unit is irradiated. In the ion implantation apparatus, at least the exposed surface other than the wafer is covered with at least one of molybdenum, tungsten, a molybdenum compound, and a tungsten compound.