Plasma processing-apparatus processing object support platform, plasma processing apparatus, and plasma processing method
According to one embodiment, a plasma processing-apparatus processing object support platform includes a lower plate, an upper plate, and a variable condenser. The lower plate is electrically conductive. The upper plate is provided on the lower plate. A processing object is placed on an upper surface of the upper plate. The variable condenser is provided along a circumferential direction of the lower plate in a region at an upper outer circumferential vicinity of the lower plate. The region has an annular configuration. The variable condenser includes a first capacitance element and a second capacitance element disposed respectively on an inner circumferential side and an outer circumferential side in the region having the annular configuration. Mutually-different control voltages are suppliable to the first capacitance element and the second capacitance element.
1. A plasma processing-apparatus processing object support platform, comprising:
a lower plate, the lower plate being electrically conductive;
an upper plate provided on the lower plate, a processing object being placed on an upper surface of the upper plate; and
a variable condenser provided along a circumferential direction of the lower plate in a region at an upper outer circumferential vicinity of the lower plate below an edge ring, the region having an annular configuration, the variable condenser including a plurality of first capacitance elements disposed on an inner circumferential side in the region having the annular configuration, and a plurality of second capacitance elements disposed on an outer circumferential side in the region having the annular configuration, a plurality of sets of one of the first capacitance elements and one of the second capacitance elements being multiply arranged along the circumferential direction, mutually-different control voltages being suppliable to the plurality of sets of the one of the first capacitance elements and the one of the second capacitance elements, the sets being arranged along the circumferential direction,
wherein the first and second capacitance elements each comprise a pair of counter electrodes and a variable capacitance is held between the pair of counter electrodes.
2. The support platform according to claim 1 , wherein
a variable capacitance unit is arranged held between the pair of counter electrodes, and
wherein the variable condenser is disposed to have an orientation in which one of the pair of counter electrodes is on a lower side and the other of the pair of counter electrodes is on an upper side.
3. The support platform according to claim 2 , wherein the control voltage is supplied between the pair of counter electrodes.
4. The support platform according to claim 2 , wherein each of the first and second capacitance elements further includes a pair of control electrodes provided at positions not interfering with the pair of counter electrodes.
5. The support platform according to claim 4 , wherein
a prescribed bias voltage is supplied between the pair of counter electrodes, and
the control voltage is supplied between the pair of control electrodes.
6. The support platform according to claim 2 , wherein the variable capacitance unit is a p-n junction-type diode.
7. The support platform according to claim 2 , wherein the variable capacitance unit is a ferroelectric.
8. The support platform according to claim 1 , wherein
the lower plate includes an upper portion, a lower portion, and a stepped portion between the upper portion and the lower portion, the upper portion being positioned on the upper plate side and having substantially a same outer diameter as the upper plate, the lower portion having a larger outer diameter than the upper portion, and
the variable condenser is disposed at the stepped portion of the lower plate.
9. A plasma processing apparatus, comprising:
the plasma processing-apparatus processing object support platform according to claim 1 ;
a gas supply unit arranged to oppose the processing object support platform;
a chamber housing the processing object support platform and the gas supply unit; and
a RF power supply supplying electrical power to the lower plate of the processing object support platform.