Miniature microwave plasma sources based on microstripline designs

Summary form only given, as follows. In the past, the challenge in microwave plasma research was to develop techniques that provide high ion and free radical densities uniformly, over large and ever increasing process areas. Since scale-up was usually an important issue when considering industrial applications, the study of very small microwave plasmas, on the order of a few millimeters, was rarely done. Recently, interest in the development of systems on a chip, MEMS and their related micro system applications, has suggested the possibility of numerous applications for mini and micro plasma sources. Accordingly, this investigation is devoted to the development and the understanding of the behavior of very small microwave plasma sources. We have constructed microwave plasma systems based on microstripline technology that create and allow for the experimental investigation of millimeter size plasmas. Plasma are generated across a wide range of input parameters, including pressure variation from below 1 Torr to 1 atmosphere, input power at 2.45 GHz from one watt to 100 watts, and a variety of gas mixtures including argon, nitrogen and hydrogen. Microwave plasmas of various sizes (volumes) and aspect ratios are studied. Plasma density, size, shape, ignition, and emission spectra are measured to characterize the miniature plasma over the operating range. Companion modeling work based on the global model is used to further understand the operation of miniature microwave plasma sources. The experimental and modeling results are used to identify the experimental operating regime necessary to excite and maintain stable, high density, miniature microwave plasma sources. Data will be presented showing the discharge power density as a function of discharge pressure, input power and size. The power densities for discharges of dimensions in the range of 2 mm to 0.4 mm range from 100´s to 1000´s W/cm/sup 3/ and the plasma densities as indicated by the global model are in the r- nge of 10/sup 13/-10/sup 14/ cm/sup -3/.