In many processes used in fabricating semiconductors the
wafer is seated on the top surface of a pedestal and heated in a
high energy process step, such as
plasma etching. The pedestal, chuck or platen may be cooling but the
wafer gradually heats until the process can no longer continue. Where large, e.g. 300 mm
diameter, wafers are being processed the temperature level across the
wafer is difficult to maintain substantially constant. In this
system and method the lateral temperature distribution is equalized by a
heat sink structure in a chamber immediately under the wafer support on top of the pedestal. A number of spatially distributed wicking posts extend downwardly from a layer of wicking material across the top of the chamber, into a
pool of a vaporizable liquid. At hot spots, vaporized liquid is generated and transported to adjacent condensation posts extending up from the liquid. The
system thus passively extracts heat to equalize temperatures while recirculating liquid and assuring adequate supply. The free volume above and within the liquid, and the short distances between posts, assure adequate
heat transfer rates.