LARGE RADIUS NEW ETCHING SYSTEM USING ELECTRON-BEAM EXCITED PLASMA

A new electron beam excited plasma (EBEP) etching system has been developed. This EBEP system can efficiently generate a high density and uniform plasma by introducing a high current low-energy electron beam into an etching gas chamber. The uniformity of the Cl plasma density is within +/-2.5% over an 8 in. wafer and the uniformity of the plasma and floating potential across the wafer is within +/-2 V. This ultrahigh uniformity of the potentials overcomes the problem of the breakdown of thin gate insulators during etching that originate from the nonuniformity of the potential at the substrate. The selectivity of etching obtained is 40:1 for poly-Si/resist and more than 100:1 for poly-Si/SiO2. The etch rate is 3600 A/min.