Patent Number: 
Section: claims

1. A plasma processing apparatus, comprising:a vacuum chamber;a plasma reactor arranged in the vacuum chamber for plasma processing;a radio-frequency (RF) power source for providing RF signals for the plasma reactor;an RF power transmission unit for transmitting the RF signals from the RF power source to the plasma reactor inside the vacuum chamber, wherein the RF power transmission unit comprises a transmission line for transmitting the RF signals and an outer conductor for shielding the electromagnetic field around the transmission line;wherein a diameter of the transmission line is larger than or equal to 10 mm; andthere is a gap of less than or equal to 10 mm between the outer conductor and the transmission line. 2. The plasma processing apparatus as claimed in claim 1, wherein the outer conductor is a conduit, a conductive foil or a metal cover. 3. The plasma processing apparatus as claimed in claim 2, wherein the vacuum chamber is provided with an inner wall, the plasma reactor is provided with an outer wall, and one end of the outer conductor is connected to the inner wall of the vacuum chamber, while the other end of the outer conductor is connected to the outer wall of the plasma reactor. 4. The plasma processing apparatus as claimed in claim 3, wherein both the outer wall of the plasma reactor and the inner wall of the vacuum chamber are conductive, and the outer wall of the plasma reactor, the inner wall of the vacuum chamber and the outer conductor provide a closed electromagnetic shielding body. 5. The plasma processing apparatus as claimed in claim 3, wherein the transmission line is in a tubular, columnar, netlike or wirelike shape. 6. The plasma processing apparatus as claimed in claim 3, wherein the transmission line is cylindrical, and the outer conductor has a cylindrical inner surface. 7. The plasma processing apparatus as claimed in claim 1, wherein a pressure in the vacuum chamber is 0.03-3 mbar, and the voltage of the RF power source is 100-500V. 8. The plasma processing apparatus as claimed in claim 1, wherein the gap is of larger than or equal to 1 mm. 9. The plasma processing apparatus as claimed in claim 8, wherein an inner diameter of the outer conductor is larger than 12 mm but smaller than or equal to 60 mm. 10. The plasma processing apparatus as claimed in claim 9, wherein the material of outer conductor comprise one or more selected from the group consisting of Cu, Au, Ag, Fe, Zn, Cr, Pb, Ti and their alloys. 11. The plasma processing apparatus as claimed in claim 10, wherein the material of transmission line comprise one or more selected from the group consisting of Cu, Al, Au, Ag, Fe, Zn, Cr, Pb, Ti and their alloys. 12. The plasma processing apparatus as claimed in of claim 1, wherein a space between the transmission line and outer conductor is filled with an insulating medium. 13. The plasma processing apparatus as claimed in claim 1, wherein the transmission line is coaxial with the outer conductor. 14. The plasma processing apparatus as claimed in claim 1, wherein the vacuum chamber is provided with a vacuum chamber pressure adjustment unit which comprises a first gas outlet. 15. The plasma processing apparatus as claimed in claim 14, wherein the plasma reactor is provided with a plasma reactor pressure adjustment unit which comprises a second gas outlet. 16. The plasma processing apparatus as claimed in claim 15, wherein the first gas outlet and the second gas outlet are connected to a same exhaust pump. 17. The plasma processing apparatus as claimed in claim 15, wherein the first gas outlet and the second gas outlet are connected to different exhaust pumps, respectively. 18. The plasma processing apparatus as claimed in claim 1, wherein the plasma reactor has an RF electrode and a first gas inlet communicated with the RF electrode. 19. The plasma processing apparatus as claimed in claim 18, wherein one end of the transmission line is connected to the RF power source, and the other end of the transmission line is connected to the RF electrode. 20. The plasma processing apparatus as claimed in claim 19, wherein the RF power source is arranged outside the vacuum chamber. 21. The plasma processing apparatus as claimed in claim 19, wherein the RF power source comprises an RF generator unit and a match box connected to the RF generator unit, and the match box serves as a conditioner for regulating a coupling power of RF signals.