Radiant energy – Irradiation of objects or material – Irradiation of semiconductor devices
Reexamination Certificate
2000-10-13
2003-05-06
Lee, John R. (Department: 2881)
Radiant energy
Irradiation of objects or material
Irradiation of semiconductor devices
C250S442110, C250S398000
Reexamination Certificate
active
06559461
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ion implantation apparatus. More particularly, the present invention relates to an ion implantation apparatus for scanning a wafer with an ion beam to implant ions into the surface of the wafer in the fabricating of a semiconductor device.
2. Description of the Related Art
In general, an ion implantation process is one of the processes used to fabricate a semiconductor device. In this process, particles of a predetermined impurity are accelerated and are formed into an ion beam directed towards a particular part of a wafer. The ion beam or the wafer is continually moved horizontally or vertically, whereby the ions are implanted into the entire surface of the wafer.
A conventional ion implantation apparatus is disclosed in Japanese Patent No. Hei 04-283923. The apparatus, as shown in
FIG. 1
, comprises: parallel ion beam radiating means
10
, a mask
16
having a slit
17
therein, a support plate
12
for supporting a wafer
11
, elevation driving means
14
for raising and lowering the support plate
12
via a driving shaft
13
integral with a bottom part of the support plate
12
, and an electrostatic flux type of charge monitor
15
disposed near the bottom of the ion beam A as it passes through the slit
17
in the mask
16
.
The parallel ion beam radiating means
10
produces an ion beam A. The ion beam A passes through the slit
17
of the mask
16
, and is accelerated by a separate speed-up pipe. Then the ions of the beam A are then implanted into the wafer
11
mounted on the support. At this time, the driving shaft
13
is raised and lowered by the elevation driving means
14
, while the support plate
12
is tilted horizontally or vertically by about 7 degrees, to execute a scanning process in the Y-direction.
Moreover, at this time, the topmost and bottommost parts of the wafer
11
are offset horizontally from each other by a distance X due to the slope of the support plate
12
. That is, there is a difference in the distance that the ion beam A propagates from the parallel ion beam radiating means
10
before reaching the topmost and bottommost parts of the wafer
11
. This difference brings about a variation in the amount of ions distributed over and hence, implanted into the wafer
11
. These variations in the amount of ions implanted into the wafer
11
create a variety of problems, such as inconsistencies in the quality of the semiconductor devices produced from the wafer. Some of the devices are even of insufficient quality.
SUMMARY OF THE INVENTION
Therefore, one object of the present invention is to solve the aforementioned problems by providing an ion implantation apparatus that minimizes the difference in distance that an ion beam must travel before reaching topmost and bottommost parts of a wafer during the scanning of the wafer, whereby the ion-implantation process is carried out uniformly across the surface of the wafer.
Another object of the present invention is to provide an ion implantation apparatus which can achieve such a uniform distribution of ions for wafers of various sizes and produce different characteristics in the wafers as the result of the ion-implantation process.
In order to achieve the aforementioned objects, the present invention provides a wafer scanning support which includes a scan shaft pivotally mounted about a horizontal axis so that it can be inclined relative to the vertical, an elevating member slidingly coupled to said scan shaft so as to be movable therealong, a driving motor for moving the elevating member up and down along the scan shaft, and a wafer holder connected to the elevating member so as to be movable therewith.
The wafer scanning support unit may also include horizontal maintaining means for positioning the wafer holder in the horizontal direction. The horizontal maintaining means includes a horizontal transfer member coupled to the elevating member so as to move therewith. On the other hand, a vertical maintaining means is provided for positioning the wafer holder in the vertical direction. The vertical maintaining means includes a vertical transfer member coupled with an end of the horizontal transfer member so as to move therewith.
The wafer holder can be incorporated into a tilter mounted to an end of the vertical transfer member. The tilter is operative to place the wafer holder in an upwardly facing position to facilitate the loading or unloading of the wafer.
According to the present invention, the scan shaft can be inclined at a predetermined position. As the elevating member is moved upwardly and downwardly along the scan shaft during scanning, the inclined wafer holder is moved along an inclined path corresponding to the inclination of the scan shaft, whereby the ion beam travels substantially the same distance to impinge all portions of the wafer including the uppermost and bottommost parts. In addition, the position of the scan shaft can be set based on the parameters of the process, such as the size of the wafer and the desired characteristics to be provided by the ion-implantation process.
Moreover, the horizontal and vertical maintaining means allow the wafer support to be moved to the same loading and unloading position irrespective of the position of the scan shaft.
REFERENCES:
patent: 3733494 (1973-05-01), Erwin, Jr.
patent: 5003183 (1991-03-01), Nogami et al.
patent: 5030835 (1991-07-01), Tamai et al.
patent: 5898179 (1999-04-01), Smick et al.
patent: 5966160 (1999-10-01), Nardone et al.
Gurzo Paul
Lee John R.
Samsung Electronics Co,. Ltd.
Volentine & Francos, PLLC
LandOfFree
Wafer scanning support unit of ion implantation apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Wafer scanning support unit of ion implantation apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Wafer scanning support unit of ion implantation apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3064072