PLASMA PROCESSING APPARATUS AND SAMPLE STAGE THEREOF
There is disclosed a plasma processing apparatus for processing a wafer put on a sample stage disposed in a processing chamber within a vacuum vessel by the use of a plasma generated in the processing chamber after mounting the wafer on the sample stage. The apparatus has heaters in areas of the interior of the sample stage which are divided radially and circumferentially. At least those of the heaters which are arranged in the areas located in the radially outer position include circumferentially arranged heater portions that are connected in series. The amounts of heat generated by these circumferentially arranged heater portions are adjusted.
1 . A plasma processing apparatus for processing a wafer using a plasma generated in a processing chamber inside a vacuum vessel after mounting the wafer on a sample stage disposed within the processing chamber, said plasma processing apparatus comprising:
a plurality of heaters disposed respectively in a plurality of areas obtained by dividing a cylindrical interior of the sample stage radially in a direction going outwardly from a center of the cylindrical interior and circumferentially about the center of the cylindrical interior; and
a control unit for adjusting amounts of heat generated by the heaters;
wherein said heaters include heaters in the areas which are arranged circumferentially at the same radius about the center; and
wherein the circumferentially arranged heaters are connected in series with DC power supplies and form a circuit and amounts of heat generated by these heaters are adjusted by the control unit.
2 . The plasma processing apparatus of claim 1 , wherein each of said heaters connected in series is connected in parallel to thereby form said circuit, and wherein the apparatus further comprises adjusting devices for adjusting amounts of current flowing through the heaters.
3 . The plasma processing apparatus of claim 2 , wherein said adjusting devices are located inside or immediately under said sample stage, and wherein the apparatus further comprises a filter which constitutes said circuit, is located among the heaters, the adjusting devices, and the DC power supplies, and is disposed outside said vacuum vessel.
4 . The plasma processing apparatus of claim 3 , further comprising electrodes made of a conductor and disposed inside said sample stage and an RF power supply for creating a bias potential above the wafer by supplying RF power to the electrodes, and wherein said adjusting devices show a much smaller impedance to said RF power than the impedance between the heaters and the DC power supplies of said circuit.
5 . The plasma processing apparatus of claim 1 , wherein the heaters arranged in the areas divided radially are electrically connected with the respective DC power supplies, and wherein electric powers supplied are adjusted by said control unit.