RESONATOR AGING REDUCTION VIA LANGMUIR - BLODGETT FILMS

CRYSTAL RESONATOR OSCILLATORS ARE COMMONLY USED FOR TIMING AND FREQUENCY CONTROL APPLICATIONS IN BOTH COMMERCIAL AND MILITARY SYSTEMS SUCH AS COMPUTERS, INSTRUMENTS, SPACECRAFT, RADIOS, ECCM, IFF, NAVIGATION, AND SURVEILLANCE MEASURES. HIGH STABILITY IS ABSOLUTELY ESSENTIAL TO SYSTEM INTEGRITY. RESONATOR AGING IS A MAJOR PROBLEM IN DEGRADING SYSTEM PERFORMANCE. TREMENDOUS COSTS ARE INCURRED DUE TO THE ADDITIONAL REQUIRED MAINTENANCE, REFURBISHMENT, ETC. IT IS A RECENT CONCEPT THAT RESONATOR AGING MAY BE SLOWED BY REDUCING MASS TRANSFER DUE TO ADSORPTION-ABSORPTION OF CONTAMINANT MATERIAL. LANGMUIR-BLODGETT (L-B) FILMS ARE MONO LAYER FILMS CAPABLE OF PREVENTING THE TRANSFER OF CERTAIN MATERIALS. IT IS PROPOSED THAT SPECIFICALLY TAILORED L-B FILMS BE APPLIED TO A RESONATOR STRUCTURE AND EVALUATED FOR MASS TRANSFER VIA ADSORPTION-ABSORPTION. ADDITIONALLY, A NOVEL APPROACH IS PROPOSED FOR OBTAINING FAST AGING DATA WITH A QUARTZ, NARROW BAND, SURFACE ACOUSTIC WAVE (SAW) BANDPASS FILTER OF REFLECTIVE MODE DESIGN. THIS TYPE OF FILTER EXHIBITS THE SAME AGING TREND AS THE COMMONLY USED BULK QUARTZ RESONATOR OR HIGH Q SAW QUARTZ RESONATOR. HOWEVER, BECAUSE OF ITS REFLECTIVE MODE DESIGN AND INHERENT SURFACE-SENSITIVE NATURE, SPECTRAL CHARACTERISTICS ARE HYPER-SENSITIVE TO MASS TRANSFER PHENOMENA. HENCE AGING OF THIS TYPE IS READILY VISBLE, ALLOWING FOR AN ACCELERATED PROGRAM. ALSO, VERY IMPORTANTLY, MANY SAW DEVICES CAN BE PRODUCED FROM A SINGLE WAFER, THUS SHARING "SAME" PROCESS VARIABLES AND EASILY ISOLATED VARIABLES.