PLASMA PROCESSING APPARATUS
In a plasma processing apparatus, a table has a wafer support to hold a wafer and a peripheral segment surrounding the wafer support and having through-holes. The peripheral segment has an upper surface lower than that of the wafer support. An outer focus ring is disposed over the peripheral segment and has a recess or a cutout at an inner portion of the outer focus ring, and the recess or cutout has through-holes. An inner focus ring is disposed in the recess or cutout of the outer focus ring. Lift pins respectively extend through the through-holes of the peripheral segment and the through-holes of the recess or cutout of the outer focus ring. Shift mechanisms control shift of the respective lift pins.
1 . A plasma processing apparatus comprising:
a table having a wafer support to hold a wafer and a peripheral segment surrounding the wafer support and having through-holes, the peripheral segment having an upper surface lower than that of the wafer support;
an outer focus ring disposed over the peripheral segment and having a recess or a cutout at an inner portion of the outer focus ring, the recess or cutout having through-holes;
an inner focus ring disposed in the recess or cutout of the outer focus ring;
lift pins respectivley extending through the through-holes of the peripheral segment and the through-holes of the recess or cutout of the outer focus ring; and
shift mechanisms to control shift of the respective lift pins.
2 . The apparatus of claim 1 , wherein the lift pins are in contact with the inner focus ring during plasma processing.
3 . The apparatus of claim 1 , wherein each of the shift mechanisms is capable of verically shifting the corresponding lift pin with a first shift precision of about 0.02 mm at a pitch of 1 mm to 2 mm and a second shift precision of about 0.1 mm at a pitch of 20 mm.
4 . The apparatus of claim 1 , wherein each of the shift mechanisms includes:
a driver;
a thruster coaxially connected to the corresponding lift pin; and
a transmitter configured to transmit a power of the driver to the thruster.
5 . The apparatus of claim 1 , wherein an inner peripheral surface and a bottom surface of the outer focus ring are insulated from the table.
6 . The apparatus of claim 1 , wherein the through-holes are disposed at substantially equal intervals in a circumferential direction of the outer focus ring.
7 . The apparatus of claim 1 , wherein the inner focus ring has a radial width in a range from 3 mm to 15 mm.
8 . The apparatus of claim 1 , wherein the inner focus ring has an inner diameter greater than an outer diameter of the wafer.
9 . The apparatus of claim 1 , wherein an upper end of an inner peripheral surface of the inner focus ring has a chamfered upper inner corner.
10 . The apparatus of claim 1 , wherein a height of an upper face of the inner focus ring is lower at an inner side of the inner focus ring than that at an outer side of the inner focus ring.
11 . A plasma processing apparatus comprising:
a table having a wafer support to hold a wafer and a peripheral segment surrounding the wafer support and having through-holes, the peripheral segment having an upper surface lower than that of the wafer support;
a focus ring disposed over the peripheral segment of the table and having an inner periphery facing an outer periphery of the wafer support;
lift pins extending through the table for raising the focus ring; and
shift mechanisms configured to control shift of the respective lift pins with one of a first shift precision and a second shift precision different from the first shift precision.
12 . The apparatus of claim 11 , wherein the first shift precision is higher than the second shift precision.
13 . The apparatus of claim 12 , wherein the first shift precision is used for raising the focus ring to a plasma processing position, and the second shift precision is used for raising the focus ring to an unloading position.
14 . The apparatus of claim 3 , wherein a moving speed in the axial direction of the lift pins during the vertical shift with the second shift precision is higher than a moving speed in the axial direction of the lift pins during the vertical shift with the first shift precision.
15 . The apparatus of claim 11 , wherein a moving speed in the axial direction of the lift pins during the control with the second shift precision is higher than a moving speed in the axial direction of the lift pins during the control with the first shift precision.