It is well known that aluminum anisotropic etching with a photoresist mask is accomplished using a sidewall passivation film which is composed of fragments of photoresist sputtered by ion bombardment. As a result, the selectivity of aluminum to photoresist is reduced under such conditions. Under these conditions, it is thought that the effect of reactive ion etching (RIE) lag becomes a serious problem. We study the dependence of the aluminum etch rate and RIE lag with photoresist and SiO2 masks on etching parameters. The RIE lag strongly depends on rf bias and the materials of the etching mask. This phenomenon corresponds to the deposition of fragments of mask material sputtered by ion bombardment on the aluminum surface. Moreover, the deposition rate strongly depends on the distance from the pattern edge of the mask. This is that the etch rate in a narrow space pattern is lower than that in an open space pattern.