Abstract: A process for selectively etching silicon comprises preparing a solution of etchant which is a non-selective etch for at least silicon and aluminum. The prepared solution is preconditioned by adding atomic silicon to the solution and aging the solution after the addition of silicon for at least 30 minutes. Then, silicon substrates carrying aluminum are immersed in the preconditioned solution to etch the silicon while leaving the aluminum substantially unaffected.

Abstract: A method for forming thin films of dielectric material which exhibit improved quality and piezoelectric response, which are formed in a DC magnetron reactive sputtering system. The dielectric material is deposited onto a substrate, and the deposition is interrupted before a highly insulating film is grown on the chamber interior. Then, the reactive gas is removed from the chamber and replaced with an inert gas, and a layer of metal is deposited on the chamber interior. This deposition of a metal layer conceals the highly insulating film on the chamber interior thereby improving the quality and piezoelectric response of the dielectric thin films. During the step of depositing a metal layer, the deposited substrate is shielded in order to prevent metal from being deposited on the substrate. Then, the deposition of dielectric material on the substrate and deposition of the metal layer on the chamber interior is repeatedly alternated until a desired thickness of the dielectric thin film has been reached.

Abstract: A cointegrated high frequency oscillator including a thin film resonator and active devices formed on the same semiconductor substrate and by a process which is compatible with formation of both the thin film resonator and the active devices. The processes utilized in formation of the thin film resonator are adapted to microelectronic processing techniques such that the steps of formation of the active devices and the thin film resonator can be intermixed to the degree necessary to allow, for example, the metallization layers to serve as elements both of the active devices and the thin film resonator.