Dielectric Breakdown and Device Evaluation of Fritted Glass Compositions

Dielectric breakdown studies have been conducted on glass compositions of interest for device passivation. It was found that a 900°C sealing glass, 50 weight percent (w/o) lead oxide, 10 w/o alumina, 40 w/o silica gave dielectric breakdown protection two to three times greater than 1 micrometer of thermal or CVD phosphosilicate glass. The dielectric strength of this glass (168 V/μm) is lower than that of thermal (780 V/μm) or CVD phosphosilicate glass (840 V/μm). When 3% or 11% is substituted for small amounts of the constituents in a , , glass, sealing temperature is lowered from 850° to 650° or 560°C, respectively. Dielectric strength is also lowered from 300 to 50 V/μm. It is shown that these low sealing temperatures, low dielectric strength glasses, could protect moat etched devices from arcing with avalanche breakdowns to a targeted 1.3 kV but reverse leakage is quite high, i.e., 300–500 μA at 1 kV. This compares to the glass with 20 μA leakage and the glass (850°C) with 10 μA leakage at 1 kV. In an attempt to obtain lower fusion temperatures and to overcome the high leakage seen with the boron‐containing glasses, a new glass without boron was made. It contains and in place of like amounts of and in the glass mentioned above. The fusion temperature was reduced from 850° to 650°C. When used on moat etched devices as a passivant, the new glass protected easily to 1.3 kV with only 10 μA reverse leakage at 1 kV similar to the parent 850°C fusing glass. The properties of this glass make it an excellent candidate as a passivant for devices where a relatively low fusion temperature is required.

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