Method and apparatus for compensating non-uniform wafer processing in plasma processing chamber

#1. Field of the Invention

#The present invention relates to the manufacture of semiconductor devices. More specifically, the present invention relates to method and apparatus for improving uniformity of wafers during plasma processing in a semiconductor plasma processing system.

#2. Description of the Related Art

#The present invention will be readily understood by the following detailed description in conjunction with the accompanying drawings, and like reference numerals designate like structural elements.

#FIG. 1 illustrates a cross-sectional view of an exemplary electrostatic chuck for clamping a wafer.

#FIG. 2A shows an exemplary graph depicting sputtering rate over a wafer.

#An invention is described herein for a method and apparatus for compensating non-uniform wafer processing in a plasma processing chamber. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be obvious, however, to one skilled in the art, that the present invention may be practiced without some or all of these specific details. In other instances, well known process steps have not been described in detail in order not to unnecessarily obscure the present invention.

#FIG. 3 illustrates an exemplary plasma processing system 300 for processing a semiconductor wafer 302 in accordance with one embodiment of the present invention. The plasma processing system 300 includes a plasma processing chamber 304, an ESC power supply 306, and a pair of RF power supplies 308 and 310. The plasma processing chamber 304 includes a shower head 312 and a bipolar electrostatic chuck 316. The shower head 312 is used to introduce source gases into a plasma region 322 over the wafer 302 in the plasma processing chamber 304. The wafer 302 is disposed and clamped over the electrostatic chuck 316 for plasma processing. A top electrode 314 may be disposed on the shower head 312 as a single assembly unit. The shower head 312 and/or electrode 314 may be made of any suitable material such as aluminum, silicon, graphite, or the like.

#The electrostatic chuck 316 includes a dielectric layer 318 formed over a metal layer 320 in a bipolar arrangement. The dielectric layer 318 may be formed of one or more dielectric materials having suitable impedance characteristics. The metal layer 320 includes a pair of poles 320A and 320B and is adapted to function as electrostatic poles (i.e., electrodes). The poles 320A and 320B are coupled to a negative and positive terminals, respectively, of the ESC power supply 306. In this manner, the pole 320A functions as a negative pole while the pole 320B operates as a positive pole. A gas (e.g., helium) is provided under pressure via one or more feed-tubes 322 through the electrostatic chuck 316 to the wafer 302. The gas acts as a cooling medium to facilitate control of the wafer temperature during plasma processing. The electrostatic chuck 316 may have other layers disposed over, under, or between the layers 318 and 320. Although a bipolar electrostatic chuck is illustrated herein, it should be borne in mind that the plasma processing system can also be used with other monopolar and bipolar electrostatic chucks having any number and types of layers.