Method and apparatus for routing harmonics in a plasma to ground within a plasma enhanced semiconductor wafer processing chamber

#1. Field of the Invention

#The present invention generally relates to plasma enhanced semiconductor wafer processing chambers. More specifically, the invention relates to the method and apparatus for routing harmonics in a plasma to ground within a plasma enhanced semiconductor wafer processing chamber.

#2. Description of the Related Art

#So that the manner in which the above recited features of the present invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof which are illustrated in the appended drawings.

#It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

#FIG. 1 depicts a schematic cross-sectional view of a prior art dual feed, cathode pedestal within a plasma enhanced semiconductor wafer processing chamber.

#FIG. 1 depicts a schematic cross-sectional view of a prior art dual feed, cathode pedestal 102 of a plasma enhanced, semiconductor wafer processing chamber 100. The cathode pedestal 102 is positioned to support a semiconductor wafer or workpiece 140 within a vacuum vessel 104. The cathode pedestal 102 comprises a housing 106, a cooling plate 108, an insulator ring 112 and an electrostatic chuck 110. The electrostatic chuck 110 comprises an electrode 114 generally formed of molybdenum mesh embedded in a ceramic body 116. The electrostatic chuck 110 is mounted to the cooling plate 108 which rests on the insulator ring 112 above the housing 106. An RF feed structure 118 is coupled through the center of the housing 106 to the chuck electrode 114. The RF feed structure 118 comprises a first conductor 120, a second conductor 122, a capacitor bank 124, and a third conductor 126.

#The first conductor 120, the capacitor bank 124 and the third conductor 126 are connected in series to couple RF power, applied to the first conductor 120 via an RF power supply 132 and RF match 134, to the electrode 114. The second conductor 122 branches from the first conductor 120 prior to the capacitor bank 124 and couples to the cooling plate 108. As such, RF power is coupled to the plasma 128 from both the electrode 114 and the cooling plate 108, i.e., a dual feed structure. The cooling plate 108 forms a first RF radiator and the electrode 114 forms a second RF radiator.

#The electrostatic chuck 110 retains a wafer 140 using a DC voltage supplied by DC power supply 136. The DC voltage is coupled to the third conductor 126 via DC conductor 130. As is well known in the art, when the DC voltage is applied to the chuck electrode 114, the wafer 140 is electrostatically attracted to the electrode 114 such that the wafer 140 is held against the support surface of the chuck 110.