Investigation of Laminated Structures for Radio Frequency Applications.
Interim technical rept. no. 5, 10 Feb-10 Sep 70,
RCA SOLID STATE DIV SOMERVILLE NJ
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A new design leading to a 40-watt high-voltage 200 volts power transistor having approximately 6 dB power gain at 400 megahertz is presented. A new double-heat-sink package was designed and tested. The parasitic capacitance was reduced from 11.8 to 1.6 picofarads in agreement with calculations 1.5 picofarads. A thermal resistance of 2Cwatt was measured. Anisotropic etching was successfully substituted for cavitroning in defining the emitter-overlay pattern. This measure allowed for a twofold increase in emitter periphery from 0.5 to 1.0 inch without changing the total device area. Basewidths of 0.3 micrometers were physically achieved for transistor structures having over 200 volts breakdown and sufficient low-frequency current gain Beta 20. Statistical analysis of all processed wafers, however, indicates that with present control, a basewidth of 0.5 plus or minus 0.2 micrometer is a more realistic value that can be consistently obtained. Thermal cycling of devices packaged in the 200-megahertz package indicate thermal fatigue resulting in leakage current increase and mechanical failure. Author
- Electrical and Electronic Equipment