Kiyotaka Ishibashi

Establishment of very uniform gas-flow pattern in the process chamber for microwave-excited high-density plasma by ceramic shower plate

The authors developed a ceramic upper shower plate used in the microwave-excited high-density plasma process equipment incorporating a dual shower-plate structure to establish a very uniform gas-flow pattern in the process chamber. Thousands of very fine gas-injection holes are implemented on this Al2O3 upper shower plate with optimized allocation to establish a uniform gas-flow pattern of plasma-excitation gases and radical-generation gases for generating intended radicals in the plasma-excitation region. The size of these fine holes must be 50μm or less in diameter and 8mm or more in length because these holes perform an essential role: They completely avoid the plasma excitation in these fine holes and upper gas-supply regions resulting from the plasma penetration into these regions from excited high-density plasma, even if very high-density plasma greater than 1×1012cm−3 is excited just under the ceramic upper shower plate by microwaves supplied from the radial line slot antenna. On the other hand, va...