John J. Maloney

Effect of Process Variables on Glass Frit Wafer Bonding in MEMS Wafer Level Packaging

Among different MEMS wafer level bonding processes glass frit bonding provides reliable vacuum tight seals in volume production. The quality of the seal is a function of both seal glass materials and the processing parameters used in glass frit bonding. Therefore, in this study Taguchi L18 screening Design of Experiment (DOE) was used to study the effect of materials and process variables on the quality of the glass seal in 6” silicon wafers bonded in EVG520IS bonder. Six bonding process variables at three levels and two types of sealing glass pastes were considered. The seals were characterized by Scanning Acoustic Microscopy (SAM), cross sectional Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Analysis (EDAX). The results were quantified into four responses for DOE analysis. Key results are a) peak temperature has the strongest influence on seal properties, b) hot melt paste has significantly lower defects compared to liquid paste, and c) peak firing temperatures can be as low as 400°C under certain conditions.

The Effect of Firing Temperature on Structure and Electrical Properties in Low Temperature Co-fired Ceramics

Abstract An LTCC tape dielectric (A6M) was fired stepwise from 775°C – 925°C using standard industry profiles. The fired tapes were investigated for shrinkage, density, crystallization (XRD), composition distribution (SEM/EDS), and high frequency (10 GHz) electrical properties. The tape consists of a glassy material that undergoes crystallization upon firing. Two crystalline phases were observed along with residual glass. Both crystallized phases appear to alter their unit cell dimensions with firing temperature. Fired tape density and XY-shrinkages were stable over the temperature range studied. Electrical properties (ϵr, tan δ) were stable above 825°C including and up to the maximum temperature studied.