HOW TUNNELING CURRENTS REDUCE PLASMA-INDUCED CHARGING

As semiconductor manufacturing moves towards smaller logic devices and thinner gate oxides, there is serious concern that pattern-dependent charging during plasma etching will impede progress by distorting etch profiles and by causing oxide breakdown. Simulations of the final ove retch predict that the use of ultrathin oxides (less than or equal to 5 nm), combined with a low substrate potential, will actually eliminat e notching by enabling electron tunneling from the substrate to decrea se surface charging potentials at the bottom of high aspect ratio tren ches, Comparison with published experimental results validates the sim ulations. (C) 1997 American Institute of Physics.