Characterization of bonded wafer for RF filters with reduced TCF

Recent development of temperature compensated SAW Devices

“…When a stiff material with small CTE is chosen as the base substrate, the bonding suppresses the thermal expansion of the top surface where SAW propagates. Various bonding technologies such as fusion [20][21][22]28], room temperature [25][26][27][28] and adhesive [23,30,31] ones, have been investigated. Although the adhesive one seems most cost-effective, it is not clear whether the adhesive is stable during and after the device fabrication.…”

“…As the base-substrate, Si [21][22][23]28,30,31], glass (fused quartz) [21][22][23][24][29][30][31], and sapphire [25][26][27] have been tested. Sapphire is most appropriate for the TCF improvement, but expensive.…”

“…In contrast, usual materials including LN and LT become soft with T, and their intrinsic TCE and TCV are negative [19,20]. Another strategy is use of the wafer bonding of a single crystal LN/LT with a stiff substrate with small CTE [21][22][23][24][25][26][27][28][29][30][31].…”

Multilayered Structure as a Novel Material for Surface Acoustic Wave Devices: Physical Insight

“…A silicon dioxide layer is required to be deposited on the LT wafer to enable a stronger bond to silicon (Abbott et al, 2005). The presence of additional SiO 2 film impacts the acoustic and electrical properties of a bonded wafer and SAW resonators built on its surface.…”

“…An example of bonded wafer will be numerically investigated in section 4. The quality of a contact between LN or LT plate and a silicon wafer can be improved if a thin SiO 2 film is deposited between these materials (Abbott et al, 2005). Such two-layered structure with IDT on the top surface is schematically shown as Type 3 in Fig.…”