IMOMEC Associated Lab IMEC Monitored In-Situduringlife Test
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Active Electronic Components Test System Application area: active electronic components Testing self-heating The application of electronics in the automotive sector comprises not only passive components as resistors, capacitors and inductors but also active devices as transistors. Transistors are called “active” because of their ability to amplify electronic signals. As the current density inside such “active” devices is generally higher than for passives, significant device self-heating occurs. This self-heating has also to be measured or at least to be known in advance in order to get reliable test results. Transistors are “three-terminal“ devices. The current through the • Constant voltage and constant current collector or drain terminal is controlled by a signal at the base or Institute for Materials Research Materials Institute for of Hasselt University Lab IMEC Associated (power) mode gate terminal. Therefore two separate power supplies for each • In-situ monitoring of all relevant device under test are needed. As the system is capable of testing 20 devices simultaneously, 40 power supplies are present. All electrical parameters relevant electrical parameters are monitored in-situ during the • Complete characterization of the device life test. during life test • Simultaneous testing of 20 devices • Dedicated acquisition software Characteristics • System furnace up to 250°C • Stress voltages up to 200 V The devices can be tested in constant voltage and constant • Monitoring of ambient temperature current (power) mode. This mode is useful to keep the device during life test internal self-heating at a constant, well-defined level. The self- • High degree of flexibility heating is a main contributor to the ageing and thus the reliabil- IMOMEC ity of active components. The ambient temperature is closely monitored during life test. The electrical stress conditions and the temperature profile are defined by a scanlist that provides a high Ic current degree of flexibility. The measurement process is controlled by dedicated acquisition Ic @ UBE-step software. This acquisition software allows also the cycling through different user-defined stress conditions, an example can be seen on the graph (right). By this way, a complete characteri- Ic-stress Ic-stress sation of the device under test during life test is possible. The system furnace is capable to operate at temperatures up to Time 250°C. Stress voltages up to 200 V can be applied to the devices cycle 1 cycle 2 under test (DUT). The electrical parameters of the DUTs are monitored in-situ during life test. Electrical stress cycle setup System description and specifications The test setup is able to stress & characterize up to 20 active components simultaneously in 3-terminal mode (e.g. transistors) or 40 2-terminal components (e.g. diodes). Parameter Specification Temperature range 30°C … 230°C Temperature stability 0.05°C Supply voltage -12V … 12 V Maximum supply current (base) 30mA (fused) Maximum supply current (collector) 300mA (fused) Maximum current measure range 1000mA Maximum measured voltage 200V Measurement resolution < 0.1% Measurement capacity 20 (3-terminal) or 40 (2-terminal) samples simultaneously Measurement example The example (right image) shows degradation of the amplification factor of heterojunction bipolar transistors (HBTs) stressed at 125mA collector current and 120°C ambient temperature. At this ambient temperature, the device internal temperature (junction temperature) is 205°C due to self-heating. Temperature dependence of the HBT thermal resistance Degradation of the HBT current amplification factor The self-heating depends on the dissipated power, the ambient temperature and the thermal resistance of the device (left image). The device self-heating has also been determined with the active electronic components measurement system. IMEC Institute for Materials Research - Hasselt University Kapeldreef 75 Division IMOMEC, IMEC vzw B-3001 Leuven Wetenschapspark 1 Belgium B-3590 Diepenbeek Belgium Ph. +32 16 28 18 80 Ph. +32 11 26 88 72 Fax. +32 16 28 16 37 Fax. +32 11 26 88 99 [email protected] [email protected].