Substrate lifting apparatus and substrate transferring method
A substrate lifting apparatus LM according to this invention is built into a stage ST having, on an upper surface, an electrostatic chuck EC for attracting a to-be-processed substrate W hands over the to-be-processed substrate to and from the stage has: lifting pins which are moveable upward and downward between a hidden position in which the lifting pins lie hidden into the stage, and a protruded position protruding upward from the upper surface of the stage; and a driving means for moving the lifting pins upward and downward. The driving means is arranged to be able to stop the upward movement of the lifting pins in an intermediate position in the course of moving the lifting pins upward from the hidden position to the protruded position.
1. A substrate transferring method comprising: a stopping step of stopping the application of voltage to an electrostatic chuck, after having processed a to-be-processed substrate in a state of being attracted by applying voltage to electrodes of the electrostatic chuck disposed on an upper surface of a stage; and a lifting step of moving upward lifting pins, built in the stage so as to be movable upward and downward to a substrate hand over position by lifting the to-be-processed substrate to the substrate hand over position above the stage;
wherein the lifting step comprises:
a first step of moving upward the lifting pins from a hidden position lying hidden into the stage until the upper ends of the lifting pins are brought into contact with a central part of the to-be-processed substrate, the lifting pins being further moved upward from the position of the contact, thereby causing such a part of the to-be-processed substrate as is lying on the electrostatic chuck to be locally lifted;
a second step of holding, for a predetermined period of time, the lifting pins in an intermediate position in which the said part of the to-be-processed substrate is lifted; and
a third step of further moving upward the lifting pins from the intermediate position to the substrate hand over position,
wherein the to-be-processed substrate is a silicon wafer and
wherein, in the first step, the height of causing the said part of silicon wafer to be locally lifted from upper surface of the stage is set above 1/500 and below 1/200 of the substrate diameter.
2. The substrate transferring method according to claim 1 , wherein the lifting pins are held for above 4 seconds in the intermediate position in which the said part of the to-be-processed substrate is lifted.
3. The substrate transferring method according to claim 2 , wherein the lifting pins are held in a range of 4 seconds and 10 seconds.
4. The substrate transferring method according to claim 1 , wherein the height is set above 1/500 and below 1/400 of the substrate diameter.