1. Field of the Invention
The present invention relates to an electrostatic chuck and a manufacturing method therefor. In particular, the invention relates to an electrostatic chuck suited to holding a plate specimen, such as a semiconductor wafer, a metallic wafer, a glass substrate or the like, using an electrostatic force, which is used in production lines for semiconductor devices, liquid crystal devices, hybrid ICs and the like, and a manufacturing method therefor.
2. Description of the Related Art
Heretofore, in production lines for semiconductor devices, liquid crystal devices, hybrid ICs and the like, in order to hold a plate specimen, for instance a semiconductor wafer such as a silicon wafer, a metallic wafer such as a thin copper plate, a glass plate or the like, for example a vacuum chuck that can suck and hold such plate specimens physically using vacuum force, or a clamp that can hold these plate specimens mechanically has been used.
However, in a conventional vacuum chuck, since under vacuum conditions there is no pressure difference between the external atmosphere and the vacuum chuck, there is a problem in that a plate specimen cannot be held. Furthermore, in a conventional clamp there are problems such as; the location where the clamp makes contact with a plate specimen cannot be used for a device, partial distortion occurs in the plate specimen, and stray particles are produced by raising and lowering of the clamp.
Therefore, in order to solve the above problems, an electrostatic chuck is proposed that enables a plate specimen to be held by using electrostatic force.
This electrostatic chuck is constructed with a circular thin internal electrode and a pair of insulating members positioned on opposite sides of this internal electrode as its main components. A plate specimen is mounted onto the mounting surface of one of the pair of insulating members, and a prescribed DC voltage is applied to the internal electrode, thereby enabling the plate specimen to be held on the mounting surface using electrostatic force.
There are two types of this electrostatic chuck, depending on the difference of electrostatic force.
One type is an electrostatic chuck using the Johnson-Rahbek effect (referred to hereunder as a Johnson-Rahbek type electrostatic chuck) as an electrostatic force, and the other type is an electrostatic chuck using the Coulomb force (referred to hereunder as a Coulomb type electrostatic chuck) as an electrostatic force.
In the abovementioned Johnson-Rahbek type electrostatic chuck, there are problems in that leakage current is great, the electrostatic attraction force varies depending on the type of plate specimen, and detachment of plate specimens is not good after removing the DC voltage.
On the other hand, the Coulomb type electrostatic chuck has characteristics in that the electrostatic attraction force hardly varies regardless of the type of plate specimen, and disattachment of plate specimens is good after the DC voltage is removed. However, in the case of executing plasma cleaning and the like, since charging up of the attachment surface occurs easily, large plasma marks accompanying this charging up are likely to occur. Therefore, there is a problem in that resistance to corrosive gases is not sufficient.