A mathematical model of a showerhead‐type reactive ion etching reactor using
SF6/O2
chemistry is developed. Experimental measurements of the plasma density, electron energy, and exit gas composition are used to provide information on the gas‐phase reactions taking place and the values for the kinetic rate constants. The concentration distributions of the various molecules and radicals are obtained by solving numerically the mass balances with finite differences. Surface recombination and competition between fluorine and oxygen atoms to adsorb on the silicon surface are considered, and the chemical etch rate of silicon is calculated. A correlation between the activation energy of the etching reaction and the energy and density of bombarding ions is obtained by comparing the calculated chemical etch rate distribution with the one measured experimentally.
The application of micro four-point probe technique in ion implantation non-uniformity mapping and analysis is demonstrated in this work. The technique uses micron-size probes with electrode pitch of 10 µm to achieve greatly enhanced spatial resolution of sheet resistance (Rs) measurements. Rs non-uniformities due to uneven dopant distribution or activation can be mapped with improved accuracy, making it easier to detect implanter scanning problems, dose and charge control malfunctions and annealer related non-uniformities. The technique's superior performance in spatial resolution over conventional four-point probe measurements is demonstrated by zero edge exclusion sheet resistance measurements at the wafer edge. In addition, the technique is used to investigate potential Rs variations between equivalent As+ and As 2 + implants with the same effective energy. Finally, repeatability and reproducibility are investigated by making multiple measurements on a selected ULE implanted and annealed wafer.
Explosive crystallization (EC) is often observed when using nanosecond-pulsed melt laser annealing (MLA) in amorphous silicon (Si) and germanium (Ge). The solidification velocity in EC is so fast that a diffusion-less crystallization can be expected.In the contacts of advanced transistors, the active level at the metal/semiconductor Schottky interface must be very high to achieve a sub-10 -9 ohm.cm 2 contact resistivity, which has been already demonstrated by using the dopant surface segregation induced by MLA. However, the beneficial layer of a few nanometers at the surface may be easily consumed during subsequent contact cleaning and metallization. EC helps to address such kind of process integration issues, enabling the optimal positioning of the peak of the dopant chemical profile. However, there is a lack of experimental studies of EC in heavily-doped semiconductor materials. Furthermore, to the best of our knowledge, dopant activation by EC has never been experimentally reported. In this paper, we present dopant redistribution and activation by an EC process induced by UV nanosecond-pulsed MLA in heavily gallium (Ga) ion-implanted high Ge content SiGe. Based on the obtained results, we also highlight potential issues of integrating EC into real device fabrication processes and discuss how to manage them.
The reactive ion etching of silicon in SF~/O2 mixtures is investigated experimentally. Electrical measurements, using a Langmuir probe, provide the plasma density of the discharge, for various settings of pressure and oxygen percentage. The plasma density ranges between 4 • 109 and 1.2 • 101~ cm -~. Information on the chemical composition of the discharge is obtained using a mass spectrometer. The lower electrode self-bias voltage ranges between 0 and 590 V and the etching rate between 100 and 17,000 A/min. The variation of the relative contribution of chemical etching and ion bombardment to the overall etching rate is demonstrated, as the process parameters are changed. Etching uniformity is also studied and the etching rate is found to be higher near the edge of the electrode. ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 142.58.129.109 Downloaded on 2015-05-30 to IP
ABSTRACTOxygen incorporation into Czochralski silicon crystals during crystal growth is influenced by reactions at the crucible interface. In the present study it was found that different dopants have different effects on these reactions, both in sealed ampuls and in Czochralski crucibles. Different reaction products and morphologies are formed along the interface depending on dopant types and levels. It was concluded that some of these reactions can affect the oxygen concentration in the melt. The dopants investigated were B, A1, Ga, In, Ge, Sn, P, As, Sb, and Bi.
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