Plasma processing method and apparatus

A capacitive coupling parallel-plate plasma etching apparatus for subjecting a target substrate to a plasma etching process, the apparatus comprising;

• a process container configured to have a vacuum atmosphere therein;
• an upper electrode and a lower electrode disposed inside the process container to face each other such that the lower electrode is configured to support the target substrate and a plasma generation space is present between the upper electrode and the lower electrode;
• an RF (radio frequency) power supply mechanism configured to apply an RF power to the upper electrode;
• a gas distribution cell disposed inside the upper electrode and configured to distribute a process gas to be supplied into the process container;
• and
• a process gas supply mechanism configured to supply the process gas into the gas distribution cell,
• wherein the upper electrode includes outer and inner upper electrodes electrically insulated from each other and disposed on a peripheral side and a central side, respectively, in a radial direction relative to a center through which a vertical line extending from a center of the target substrate passes, such that the inner upper electrodes faces the plasma generation space essentially all over the target substrate, the outer upper electrode surrounds the inner upper electrode and is positioned radially outside an outer peripheral edge of the target substrate, and outer and inner RF discharge regions are defined by the outer and inner upper electrodes, respectively,
• the RF power supply mechanism includes a common RF power supply connected to the outer and inner upper electrodes and configured to output the RF power, and an electricity feeding structure configured to supply the RF power from the common RF power supply to the outer and inner upper electrodes and to cause the RF power to be discharged toward the plasma generation space from the outer and inner RF discharge regions at a predetermined ratio, so as to control spatial distribution of density of the plasma relative to the target substrate,
• the electricity feeding structure includes:
• a central conductive member connected to a central portion of the inner upper electrode;
• a first cylindrical conductive member surrounding the central conductive member and substantially continuously connected to the outer upper electrode in an annular direction;
• a conductive connector connecting the first cylindrical conductive member to the central conductive member;
• and a second cylindrical conductive member surrounding the first cylindrical conductive member and connected to ground potential, such that the RF power is divided by the conductive connector and transmitted to the central conductive member and the first cylindrical conductive member, and such that an outer coaxial pass is formed as a waveguide between the second cylindrical conductive member and the first cylindrical conductive member, and an inner coaxial pass is formed as a waveguide between the second cylindrical conductive member and the central conductive member,
• the gas distribution cell is internally divided by an annular partition member into outer and inner gas supply cells on a peripheral side and a central side, respectively, in the radial direction,
• the inner upper electrode includes a plurality of gas delivery holes formed therein and communicating with the outer and inner gas supply cells, such that an outer gas delivery region is defined by a first portion of the plurality of gas delivery holes communicating with the outer gas supply cell and an inner gas delivery region is defined by a second portion of the plurality of gas delivery holes communicating with the inner gas supply cell, and thus the outer and inner process gas delivery regions are present on a peripheral side and a central side, respectively, in the radial direction on the inner RF discharge region,
• the outer upper electrode has no gas delivery holes formed therein, and thus the outer RF discharge region includes no process gas delivery region, and
• the process gas supply mechanism is configured to cause the process gas to be delivered toward the plasma space from the outer and inner process gas delivery regions at a predetermined ratio, so as to control spatial distribution of density of radicals in the plasma relative to the target substrate independently of the spatial distribution of density of the plasma.