Electronic device and method for producing the same

#1. Field of the Invention

#The present invention relates to an electronic device and a method for producing the same. In more detail, the present invention relates to an electronic device such as a semiconductor integrated circuit, a semiconductor device or a surface acoustic wave (SAW) device, and a method for producing the same.

#2. Description of the Related Art

#FIGS. 1A and 1B are cross sectional views showing the reactive ion etching steps using a chlorine-based gas in the conventional art.

#FIG. 2 is a cross sectional view of a substrate damaged by over-etching.

#FIGS. 3A to 3F are cross sectional views showing the electrode forming steps according to one embodiment of the present invention.

#The inventor of the present invention have found, through collective studies, that the damage of the substrate is not simply caused by physical damage due to collision of ions onto the substrate, but is caused by a diffusion of chlorine species (ions, atoms, molecules or chlorine radicals) into the substrate. According to the study, it is thought that chlorine is diffused into the substrate by exposing the surface of the substrate to the chlorine ions during the reactive ion etching and destroys or impairs the crystallinity of the substrate. As a result, various properties which were appeared due to high crystallinity, such as piezoelectric properties, dielectric properties, pyroelectric properties, semiconductor properties, magnetic properties or the like are caused to degrade.

#The method and the electronic device according to the present invention were based on the facts found by the inventors of the present invention, providing an electronic device in which a lower electrode layer comprising a material capable of reactive ion etching with a fluorine-based gas is formed on a single crystal substrate or single crystal film, or on a triaxial or uniaxial orientation film, and an upper electrode layer comprising a material capable of reactive ion etching with a chlorine-based gas being formed on the lower electrode layer. Functional single crystal materials such as piezoelectric materials, dielectric materials, pyroelectric materials, semiconductors materials and magnetic materials are used for the single crystal substrate or single crystal film, or for the triaxial or uniaxial orientation film depending on the kind of the electronic device.

#According to the study by the inventor, the present invention is more preferably applied to an surface acoustic wave device having a piezoelectric substrate or film made of a material such as LiTaO3, LiNbO3, Li2B4O7, quartz or La3Ga5SiO14 (Langasite) and the manufacturing method thereof. This is because these materials are susceptible to chlorine diffusion by the reactive ion etching to result in degradation of the piezoelectric properties.