Plasma processing apparatus and plasma processing method

1. A plasma processing apparatus comprising:

a process container configured to hold a vacuum therein and perform a plasma process on a target object accommodated therein, the process container including a container casing that is equipped with an upper plate disposed on an upper side thereof and defining a top opening, and a dielectric transmission plate supported by the upper plate and airtightly closing the top opening;

a worktable configured to place the target object thereon inside the process container;

a planar antenna disposed above the transmission plate and including a plurality of slots to supply microwaves from the slots through the transmission plate into the process container;

a gas feed member configured to supply a process gas, to be turned into plasma by the microwaves, into the process container;

an exhaust line configured to exhaust gas from inside the process container;

a dielectric wave-retardation body disposed above the planar antenna and configured to shorten a wavelength of the microwaves; and

a metal cover covering the planar antenna and the wave-retardation body,

wherein the planar antenna is fixed at a periphery of the planar antenna to the metal cover by fixing members, which are fitted in a recess formed on the transmission plate at a periphery of the transmission plate, and

the transmission plate is set at a position where the transmission plate is separated from the target object placed on the worktable by a distance of from 20 mm to 100 mm.

2. The plasma processing apparatus according to claim 1 , wherein the recess is formed as an annular recess on the transmission plate at a periphery of the transmission plate.

3. The plasma processing apparatus according to claim 1 , wherein the transmission plate includes a dished recess formed on a lower surface facing the target object, and the distance is defined by a distance between the target object and a thin portion of the transmission plate corresponding to the dished recess.

4. The plasma processing apparatus according to claim 3 , wherein the thin portion of the transmission plate has a thickness of λg/4 or more, where λg is the wavelength of the microwaves.

5. A plasma processing apparatus comprising:

a process container configured to hold a vacuum therein and perform a plasma process on a target object accommodated therein, the process container including a container casing that is equipped with an upper plate disposed on an upper side thereof and defining a top opening, and a dielectric transmission plate supported by the upper plate and airtightly closing the top opening through a first seal member;

a worktable configured to place the target object thereon inside the process container;

a planar antenna disposed above the transmission plate and including a plurality of slots to supply microwaves from the slots through the transmission plate into the process container;

a gas feed member configured to supply a process gas, to be turned into plasma by the microwaves, into the process container;

an exhaust line configured to exhaust gas from inside the process container;

a dielectric wave-retardation body disposed above the planar antenna and configured to shorten a wavelength of the microwaves;

a metal cover covering the planar antenna and the wave-retardation body;

a first presser member that presses the transmission plate to the upper plate via a first fixing member, the first presser member being set in contact with the transmission plate at a periphery of the transmission plate with a second seal member interposed between the first presser member and the periphery of the transmission plate, and the first presser member being in contact with a top portion of the upper plate with a third seal member of a metal seal ring interposed between the first presser member and the top portion of the upper plate; and

a second presser member that presses the metal cover to the first presser member via a second fixing member, the second presser member being set in contact with the metal cover at a periphery of the metal cover with a fourth seal member of a metal seal ring interposed between the second presser member and the periphery of the metal cover, and the second presser member being in contact with the first presser member with a fifth seal member of a metal seal ring interposed between the second presser member and the first presser member,

wherein the transmission plate is set at a position where the transmission plate is separated from the target object placed on the worktable by a distance of from 20 mm to 100 mm.

6. The plasma processing apparatus according to claim 5 , wherein the planar antenna is fixed at a periphery of the planar antenna to the metal cover by fixing members, which are fitted in a recess formed on the transmission plate at a periphery of the transmission plate.

7. The plasma processing apparatus according to claim 6 , wherein the recess is formed as an annular recess on the transmission plate at a periphery of the transmission plate.

8. The plasma processing apparatus according to claim 5 , wherein the transmission plate includes a dished recess formed on a lower surface facing the target object, and the distance is defined by a distance between the target object and a thin portion of the transmission plate corresponding to the dished recess.

9. The plasma processing apparatus according to claim 8 , wherein the thin portion of the transmission plate has a thickness of λg/4 or more, where λg is the wavelength of the microwaves.