Plasma processing apparatus capable of suppressing variation of processing characteristics

Abstract

A plasma processing apparatus includes a reaction container with the inner side wall thereof insulated, a sample rest and an antenna arranged in the reaction container. The high-frequency power is supplied to the antenna from a plasma generating power supply, the processing gas is introduced into the reaction container and converted to a plasma, and the sample placed on the sample rest is processed by the plasma. A matching unit for securing the impedance matching is inserted between the plasma generating power supply and a load circuit including the antenna. The matching unit includes a sensor for measuring the impedance characteristic on the load circuit side and a unit for changing the match point and the matching track leading to the match point on the input side of the matching unit in accordance with the measurement by the sensor.

1 . A plasma processing apparatus comprising:
 a reaction container with the inner side wall insulated and having arranged therein a sample rest, wherein the reaction container is supplied with high-frequency power from a plasma generating power supply to convert the processing gas introduced into said reaction container into a plasma thereby to process a sample on said sample rest with said plasma;   a matching unit for impedance matching between said plasma generating power supply and a load circuit for said plasma generating power supply; and   a database for storing in advance a predetermined match point (a 1 ) corresponding to an input voltage reflection coefficient of zero (0 W of a reflected wave) on a Smith chart and a matching track (a 1 ) leading to the predetermined match point (a 1 ), and also storing in advance shifted points (a 2  . . . an) and tracks (a 2  . . . an) leading to the shifted points (a 2  . . . an) respectively, each of the shifted points (a 2  . . . an) corresponding to an input voltage reflection coefficient of not zero, and being shifted from the predetermined match point (a 1 ) so as to stabilize the plasma, suppress a characteristic variation of the plasma processing and avoid an unstable area of the plasma;   wherein said matching unit includes a sensor for measuring the impedance characteristics of said load circuit as a voltage reflection coefficient which changes with an increase in a number of samples being processed, and a means for changing the predetermined match point (a 1 ) and the matching track (a 1 ) leading to said predetermined match point one of the shifted points (a 2  . . . an) and one of the tracks (a 2  . . . an) which leads to the one of the shifted points (a 2  . . . an), in accordance with the measurement result of said sensor with reference to the database.