JPH0748369B2 - Ion implanter - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ion implantation apparatus used in a manufacturing process of a semiconductor integrated circuit, and more particularly to an ion implantation apparatus that emits secondary electrons to suppress wafer charge-up. Regarding injection device.

[Conventional technology]

Conventionally, this type of ion implanter has provided both an electron gun that emits primary electrons and a target that emits secondary electrons due to collision with primary electrons from the electron gun to the ion beam line side from the wafer holding position. It was common to prepare for.

[Problems to be Solved by the Invention]

In the above-described conventional ion implanter, both an electron gun that emits primary electrons and a target that emits secondary electrons due to collision with primary electrons from the electron gun are placed on the ion beam line side from the wafer holding position. Since it is provided, the distance between the wafer and the target becomes large, the secondary electrons emitted from the target have a low probability of reaching the surface of the wafer, and the secondary electrons cannot be effectively used. There is also a drawback that primary electrons from the electron gun are injected into the wafer and change the conductivity type, which adversely affects the semiconductor device.

[Means for Solving the Problems]

The ion implantation apparatus of the present invention includes an electron gun and one
An ion implanter having a target that emits secondary electrons to the surface of a wafer by irradiation of secondary electrons, wherein the target is placed immediately above the outer peripheral portion of the surface of the wafer,
The electron gun is installed on the back side of the wafer.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of the first embodiment of the present invention.

In FIG. 1, 1 is a wafer holder made of an Al plate or the like provided with a passage hole for passing the primary electrons emitted by the electron gun 3, and 2 is a collision with the primary electrons 5 emitted by the electron gun 3. Targets that emit secondary electrons 6 at this time, 4 is a wafer, 7
Is a positive ion beam.

The electron gun 3 installed on the back side of the wafer 4 causes primary electrons 5
Is emitted and irradiated in the direction of the target 2,
The primary electrons 5 pass through the through holes of the wafer holding unit 1 and collide with the target 2 installed right above the outer peripheral portion of the wafer surface. The colliding primary electron 5 changes its movement direction and simultaneously emits a secondary electron 6. Then, when the ion beam 7 is incident on the wafer 4 and the surface of the wafer 4 is positively charged, the secondary electrons 6 emitted from the target 2 are adsorbed to the wafer 4 and suppress the charge-up of the wafer 4.

In the first embodiment having such a configuration, the target 2 can be brought close to the wafer 4, so that the secondary electrons can be effectively used. Further, since the electron gun 3 is provided on the back surface of the wafer 4, the primary electrons 5 are not directly injected into the wafer 4.

FIG. 2 is a cross-sectional view of the second embodiment of the present invention, showing the case where the present invention is applied to an ion implantation apparatus in which the wafer holder 1 makes a motion such as rotation.

In FIG. 2, a target 2 is provided immediately above the outer peripheral portion of the surface of a wafer 4 held by a wafer holder 1 made of an Al plate or the like. The electron gun 3 is provided on the back surface side of the wafer 4.

Also in the second embodiment having such a configuration, the first
As in the case of the above embodiment, since the target 2 that emits secondary electrons can be brought close to the wafer 4, the secondary electrons can be effectively used. Further, since the primary electrons 5 from the electron gun 3 pass through the outer peripheral portion of the wafer holder 1, there is an advantage that the wafer 4 can be rotated.

〔The invention's effect〕

As described above, according to the present invention, the target is placed right above the outer peripheral portion of the wafer surface, and the electron gun is placed in the direction of the back surface of the wafer, so that the distance from the wafer surface can be reduced to 2
Since the secondary electrons can be supplied to increase the probability that secondary electrons exist near the surface of the wafer, there is an effect that the charge-up of the wafer can be suppressed while efficiently using the secondary electrons.

[Brief description of drawings]

FIG. 1 is a sectional view of a first embodiment of the present invention, and FIG. 2 is a sectional view of a second embodiment of the present invention. 1 ... Wafer holder, 2 ... Target, 3 ... Electron gun, 4 ... Wafer, 5 ... Primary electron, 6 ... Secondary electron, 7 ... Ion beam.

Claims (1)

[Claims] 1. An ion implanter having an electron gun and a target that emits secondary electrons onto a wafer surface by irradiating primary electrons from the electron gun, wherein the target is placed immediately above the outer peripheral portion of the wafer surface, and An ion implanter, wherein the electron gun is installed on the back side of a wafer.