Electron beam control rf discharges for plasma processing

Abstract

Summary form only given. Reactive ion etching (RIE) discharges for microelectronics fabrication suffer from the inability to separately control plasma density and ion power flux to the wafer. Inductively coupled plasma (ICP) and electron cyclotron resonance (ECR) reactors have been developed to provide some degree of independent control. This is accomplished by arranging for ionization to be provided dominantly by the applied electromagnetic instead of the rf bias to the substrate. Both ICP and ECR reactors, though, optimally operate at low gas pressures (<10 s mTorr), and are not typically used for intermediate to high pressure etching and deposition systems (10 s-100 s mTorr). To address the higher pressure range, a hybrid electron beam/RIE discharge system (EB-RIE) has been developed In the EB-RIE system, a planar electron beam (1-3 kV) is injected into the plasma chamber above and parallel to the wafer. An rf bias is separately applied to the substrate. For appropriate combinations of e-beam energy and gas pressure, the e-beam can dominantly provide the ionization and dissociation of the gas, while the rf bias can be used to independently control the ion power flux to the wafer. A 2-dimensional model of the EB-RIE reactor has been developed to investigate the scaling of the device and analyze previous experimental measurements. The model is a hybrid plasma equipment model (HPEM) which combines an electron Monte Carlo module with a fluid simulation.