JPS6459860A - Preparation of ion implantation mask - Google Patents

Abstract

PURPOSE:To enable the material to be an ion implantation mask to be formed on the sidewall of a polycrystalline silicon electrode, by employing a series of processes in which the temperature of a wafer is lowered to the condensation temperature of a source gas at a predetermined pressures to condense the gas on the surface of the wafer, the condensation layer is then resolved into a deposition layer by a light illuminating or a plasma. CONSTITUTION:When the temperature of a substrate is lowered to the condensation temperature of a source gas, the source gas is condensed into liquid on the surface of the substrate. At this time, the liquid so starts the deposition thereof from the place in which the liquid can have the minimum surface area as to minimize the surface energy thereof. For example, when a trench is previously formed in the silicon substrate 31 and the source gas is made to condensed into liquid thereon, the liquid 32 starts the deposition thereof from an angular bottom. Now, the condensation layer, which is deposited on the bottom, is illuminated with light to be resolved into a solid layer. Similarly, the cooling of a sample may be performed within a plasma system. Accordingly, the ion implantation mask suitable for an LDD structure can be made of the solid film deposited on the such the angular bottom without an etching process therefor being employed.