Low-damage etching using an electron-beam (EB)-induced surface reaction (EB-assisted dry etching) is studied. Low-energy and high-current density EB is obtained from argon (Ar) initiated electron-cyclotron-resonance (ECR) plasma. The rate of EB-assisted dry etching, showering 120 eV EB onto a GaAs substrate in a 1 X 10(-4) Torr chlorine gas (Cl2) atmosphere, is more than ten times larger than that for Cl2 gas etching. A 0.4 mum linewidth fine structure in GaAs was transferred. Etching of AlGaAs in Cl2 and the selective etching of GaAs from AlGaAs through the addion of SF6 gas into Ar-ECR plasma have been performed. The degree of damage induced by EB-assisted dry etching is optically and electrically characterized using a GaAs/AlGaAs quantum well (QW) structure and a two-dimensional electron gas (2DEG) heterostructure samples, respectively. The results were compared with those of samples, prepared by ion-beam-assisted etching (IBAE). It is shown that EB-assisted dry etching does not degrade these properties, whereas for IBAE, reduction of both PL intensity from a QW and hall mobility in a 2DEG are observed.