Study of the ageing characteristics of III/V electronic components using high-resolution in-situ measurements

Abstract

The initial goal of the development of the in-situ test system was the shortening of test times from 4000 hours to a fortnight. Point of departure was the High Resolution Resistance Measurement technique (HRRMT) which had been developed at the Instituut voor Materiaalonderzoek (Institute of Materials Research, IMO) for the exploration of the ageing of passive material systems. A study of feasibility performed on commercial electronic components showed the applicability of the method to active components as the measurement accuracy was of the same order than it has been achieved with the HRRMT on passive components. The first design of the measurement system was based on analogue voltage and current supplies and offered only limited versatility as every change of the stress conditions resulted in time-consuming hardware adaptations. In-situ accelerated life tests were then successfully demonstrated with MESFET structures which were known to be subject to gate sinking when put under thermal stress. The degradation of the MESFETs for a timescale of 4000 hours could then be forecasted based on an in-situ life-test of 60 hours for a timescale of 4000 hours which corresponds to the duration of conventional tests. With the application of the in-situ method to active electronic components, the issue of device self-heating was encountered. Under standard operating conditions, significant device self heating occurs. As many ageing processed are stimulated by temperature, the channel or junction temperature at life test conditions must be determined. An improved method has been developed to measure the thermal resistance of MESFETs under capacitive load and the method has been applied to MMIC amplifier modules. At this stage the different stress and measurement parameters were still realised by analog supplied which must be multiplexed. This multiplexing rendered the measurement process complex and prone to hazard. With the development of dedicated, digitally controlled power supplies and some necessary triggering and timing circuitry, the test bench system was extended toward full software control. This software controlled measurement system offered much more versatility as stress and measurement profiles could be adapted without effort. This novel test bench has been applied on pHEMT devices. ...