The neutral flux in the plasma etching of semiconductor wafers has been derived analytically for a simplified model for a circular cylindrical trench hole (circular via). The neutral molecules obey a Maxwellian distribution function and mutual collisions are neglected in the trench. Scattering of the neutrals with the sidewalls and trench bottom is ignored. The flux vector is given at each point on the etching profile surface. The flux vector reduces to the expression previously determined at the center of the trench. Etching profiles of the trench are displayed for neutral flux‐limited etch rates.