Abstract: Inductively coupled plasma （ICP） etching of InP was performed using Cl₂/Ar. The effects of dc bias, ICP power, total flow rate and Cl₂:Ar ratio on etch rate and surface morphology are discussed. It is found that the Cl₂:Ar ratio is essential to increase etching rate and smooth etched surface. When Cl₂ content is about 30%, there is a fine balance between the ion bombardment and the chlorine reaction, where the etching rate is close to peak value and the surface is the smoothest. The SEM image shows smooth etched surface and vertical sidewall.