1. Field
Example embodiments relate to an apparatus for fabricating a semiconductor device, and for example, to an apparatus and/or a method for controlling an ion beam, and/or to a method for preparing an extraction electrode for the same.
2. Description of Related Art
An ion beam apparatus using a plasma as an ion source has been utilized in a processing apparatus for a semiconductor device. In the ion beam apparatus, a plurality of extraction electrodes in which a plurality of extraction holes may be formed may be disposed at an extraction terminal of the ion source. A voltage may be applied between the extraction electrodes to extract an ion beam from the ion source.
In a semiconductor process using an ion beam, the uniformity of the ion beam has a great effect on the uniformity of the semiconductor process. Accordingly, it may be very important to control the uniformity of the ion beam. Generally, a repulsive force between charged particles included in an ion beam may increase a divergence toward an edge of the ion beam, and a flux of the ion beam may decrease toward the edge. Because a density of a plasma for extracting the ion beam may decrease from a center of the plasma toward an edge of the plasma, the uniformity of the ion beam may decrease. A neutral beam generated from the ion beam may have the same uniformity as that of the ion beam.
FIG. 1 illustrates an ion beam apparatus 10 for obtaining a uniform ion beam I according to the conventional art. The ion beam apparatus 10 may include an ion source P including a plasma chamber 11. An extraction electrode 12 may have an extraction hole at an edge 12b of the plasma chamber 11 and/or an extraction hole at a center 12a of the plasma chamber 11. According to the conventional art, in order to increase the uniformity of the ion beam I, there is proposed a method to differentiate a diameter of the extraction hole at the edge 12b of the plasma chamber 11 from a diameter of the extraction hole at the center 12a of the plasma chamber 11. However, it may be difficult to fabricate an extraction electrode 12 with spatially different diameters for extraction holes. When spatial distribution of the ion beam I changes according to a change in a process condition, different extraction electrodes may need to be fabricated. Accordingly, a process window capable of changing a process condition may be considerably limited.
In conventional semiconductor devices, because a size of the extraction electrode has been increased according to an increase in a wafer size, the aforementioned method may increasingly have difficulty in controlling the uniformity of the ion beam.