Static electricity means a state in which electricity is static. When electrostatic charge (positive charge) is in close proximity to a conductor such as plasma, a negative charge in the conductor is drawn, giving the surface of the conductor a charge.
E.S.C. is similar in principle to a condenser which is a device that stores charges. When voltage is applied to two parallel metal plates facing each other, the electrode plate with the positive electrode receives a positive charge while the electrode plate with the negative electrode receives a negative charge. And this is when the electrostatic force is generated between the two parallel plates.
E.S.C. is where the substrate lies within the vacuum chamber of the semiconductor/display manufacturing equipment. Since the substrate is fixed to the lower electrode by the static electricity, E.S.C. has no clamp that causes particulate contamination in the mechanical chuck. When +/- electricity is applied to E.S.C., the opposite potential is charged to the object, and the force attracting each other is generated by the charged potential.
The flatness of the wafer surface is guaranteed as the wafer is fixed by the electrostatic force which is evenly spread across the contact surface with the wafer. It is easy to adjust the temperature because the wafer comes into close contact with the entire surface of E.S.C. to effectively release its heat.