A measurement of the electron energy distribution function (EEDF) using the ac superposition method is done over a helium pressure range of 10-100 mTorr in a planar inductive plasma, and the electron energy diffusion coefficient which describes the electron heating is calculated based on the same discharge conditions using a two-dimensional simulation. It is found that the measured EEDF shows a bi-Maxwellian distribution with a low-energy electron group at low pressures below 20 mTorr even in the inductive discharge using helium of the non-Ramsauer gas. The major factors which can affect the EEDF formation are investigated. In particular, the concept of the total electron bounce frequency, i.e., the electron residence time, is introduced as an indicator of how the electron-electron collision affects the EEDF shape. As a result, it is shown that the observed bi-Maxwellian distribution at low pressures is attributed to the combined effects of the formation of low-energy electrons through the cooling mechanism of energetic electrons enhanced by the capacitive field, the low heating rate of the low-energy electrons, the confinement of low-energy electrons by the ambipolar space potential, and the low electron-electron collision frequency which can be estimated from the total electron bounce frequency presented in this paper.

Studies on electron heating are done during the power coupling change in the discharge mode transition (E–H mode transition) in a planar inductive argon discharge without electrostatic screen (Faraday shield). The electron energy distribution function (EEDF) evolution is measured by the alternating current superposition method with a radio frequency (rf) compensated Langmuir probe. The trend of its integrals, electron density and effective electron temperature, and especially the plasma potential against rf power are presented. It is demonstrated that the plasma potential is governed primarily by the high-energy electron tail in a plasma with bi-Maxwellian EEDF. The interdependence of the EEDF and the plasma potential is discussed. The experimental results show that the plasma potential against rf power reflects a change in the relative contribution of capacitive power coupling to electron heating.

In high-frequency inductively coupled argon discharges with a planar-type coil the phenomena of discharge mode transition (E–H mode transition) are investigated. Experimental observation is done at the low pressure of 10 mTorr and the high frequency of 19 MHz over a range of rf power, 40–525 W. First of all, the discharge mode transition is observed through a change of luminous intensity. This transition is found to occur at the relatively high power of about 280 W compared with the mode transition in a 6.5 MHz discharge. Also, some distinctive features are compared to low-frequency discharges during this transition. In particular, during the E–H mode transition the apparent changes of plasma potential are observed and the sudden variation of plasma potential is proposed as an important factor that indicates the change of power coupling. The features of the discharge mode transition in high-frequency discharge are discussed by considering the power coupling at each mode by measurements of the electron energy distribution functions.

Articles you may be interested inLow energy electron heating and evolution of the electron energy distribution by diluted O 2 in an inductive Ar / O 2 mixture discharge Evolution of an electron energy distribution function in a weak dc magnetic field in solenoidal inductive plasmaThe evolution of the electron energy distribution function ͑EEDF͒ over a pressure range of 5-100 mTorr is investigated in a planar inductive argon discharge. It is found that the EEDF, which appears to be a bi-Maxwellian distribution with a two-temperature structure at low pressures, evolves into a Druyvesteyn-like distribution as the pressure increases. The electron energy diffusion coefficient, which describes electron heating, is calculated under the same discharge conditions using discharge parameters and numerical results show that the heating of low-energy electrons is enhanced as the pressure increases resulting in a transition of the EEDF to a Druyvesteyn distribution.

We have developed a 1.29~12 full CMOS SRAM cell for low power applications, which is the world-smallest one by using 0 . 1 2~1 single gate CMOS technology and optical enhancement techniques for extending use of 248nm KrF lithography. It includes 1) 0.28um pitch contacts formed by aerial image controlled patterns on phase shift mask (PSM) and photo resist flow, 2) gate patterns with 0.24um pitch, 3) 0 . 1 3~ buried channel PMOS, and 4) spacer-on-stopper (SOS) MOSFET structure for expanding contact area and reducing band-to-band tunneling leakage.

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