Process for the production of dielectric thin films; pyroelectric sensor

摘要

A process for producing a dielectric thin film of a compound oxide of a high-melting metal and a low-melting metal by vapor-depositing the compound oxide onto a substrate, characterised in that said substrate or the vapour phase is irradiated with a laser beam during vapour deposition. The vapour deposition of the compound oxide onto the substrate may be carried out by irradiating the compound oxide as a target with a laser beam. The laser beam irradiating the substrate or vapour phase, 11, has a higher energy than the laser irradiating the target 6 (Fig 1). Specific examples of compound oxides are Pb(Zr, Ti)O3; (Pb, La) (Zr, Ti)O3; (Pb, La)TiO3; BaTaO3; LiTaO3; and LiNbO3, and may be deposited by sputtering, CVD, molecular beam epitaxy and electron beam methods. In one method evaporation is carried out in an oxygenous atmosphere with a partial pressure of oxygen of 0.06 Torr or more. There is also provided a pyroelectric type of sensor (Fig 11) comprising: a MOS element including a drain electrode (5), a source electrode (6), a gate electrode (7) and an Si semiconductor and a film of a ferroelectric or pyroelectric material formed on the drain electrode, the drain electrode being made of a material which exhibits a good ohmic contact with Si or SiO2 and has a latice constant close to that of ferroelectric or pyroelectric material. The film of ferroelectric or pyroelectric material may be obtained by irradiating a target comprising a compound oxide of a high-melting metal and a low-melting metal with a laser beam to vapour-deposit the compound oxide onto said drain electrode. The drain electrode may be made of two materials, the part connected to the Si semiconductor made of a material that exhibits a good ohmic contact with Si or SiO2 eg Al, and the other part on which the film of ferroelectric or pyroelectric material is to be formed made of a material that has a lattice constant close to that of the ferroelectric or pyroelectric material, eg Pt. The MOS element may be used in a liquid crystal display. IMAGE