Patent ID: 9704731
Date: 2017-07-11
CPC Classifications: H01J,H01L

Claim:
1. A plasma processing method for processing a sample that is an object to be processed by plasma, by mounting the sample on an upper surface of a sample stage arranged in a processing chamber inside a vacuum container and forming the plasma in the processing chamber, the sample stage including a refrigerant inlet and a refrigerant outlet arranged in each of a plurality of refrigerant channels that are concentrically arranged inside the sample stage and configured to allow a refrigerant to flow inside, and configured to function as a first evaporator, wherein the sample stage is included in a refrigeration cycle including a plurality of upstream-side expansion valves and a plurality of downstream-side expansion valves connected to the respective refrigerant inlets and the respective refrigerant outlets to adjust a flow rate or a pressure of a refrigerant flowing into the respective refrigerant inlets and a flow rate or a pressure of a refrigerant flowing out from the respective refrigerant outlets, in which a compressor, a condenser, the plurality of upstream-side expansion valves, the plurality of refrigerant channels, the plurality of downstream-side expansion valves and a second evaporator are connected in this order via a refrigerant duct to allow the refrigerant to flow therethrough in the recited order, the method comprising: adjusting openings of the plurality of upstream-side expansion valves and openings of the plurality of downstream-side expansion valves so that no change in flow rate of the refrigerant occurs in a plurality of refrigerant paths between the plurality of upstream-side expansion valves and the plurality of downstream-side expansion valves via the plurality of refrigerant channels; wherein the plurality of refrigerant channels includes a center-side refrigerant channel arranged on a center side of the sample stage and an outer periphery-side refrigerant channel arranged on an outer periphery side of the sample stage; and wherein the method further comprises adjusting openings of the plurality of upstream-side expansion valves and the openings of the plurality of downstream-side expansion valves so that a sum of reciprocals of refrigerant conductances of the upstream-side expansion valve and the downstream-side expansion valve connected to the center-side refrigerant channel is equal to a sum of reciprocals of refrigerant conductances of the upstream-side expansion valve and the downstream-side expansion valve connected to the outer periphery-side refrigerant channel.