Radiation damage in dry etching

Submicrometer structures in GaAs and Si have been defined by a number of dry etching techniques which provide anisotropic etch profiles. In addition to etch anisotropy, an important consideration for device and circuit fabrication is whether the process introduces damage in the material or causes degradation in the electrical performance of devices. In dry etching, the directionality of the etch profiles depends on the bombardment of surfaces with energetic ions; therefore, devices potentially can suffer radiation damage. Contamination originating from polymer formation during etching or materials sputtered from the etching chamber can also influence device performance. Also, preferential etching or layer intermixing of compound semiconductors can cause stoichiometry modifications. In this paper, factors that influence damage in dry etching are reviewed. Dry etching techniques including reactive-ion etching, sputter etching, ion-beam etching, and ion-beam-assisted etching in Si and GaAs have been investigated. Damage induced in semiconductor substrates was evaluated by fabricating Schottky diodes and metal-oxide-semiconductor capacitors on the etched surfaces. Induced damage in semiconductors was found to depend on ion energy, etching species, and etching chamber configuration. Damage can be minimized by using the optimal etching condition and chamber design. Techniques which can be used after dry etching to remove damage are also discussed. © 1986.