Agilent engineer wins CS Mantech award
Agilent Technologies Tom Low has won this year s CS Mantech best paper award for a study that proves that defects are responsible for infant failure in HBTs.
The paper s key result, which has implications for all HBT manufacturers, was that the probability of infant failure is equal to the product of the HBT emitter s area and the etch pit density of the underlying substrate.
Agilent produces circuits with hundreds of HBTs for its range of test and measurement equipment products, and one outcome of this research is to specify low etch pit density (EPD) material from its key substrate supplier, AXT.
Lower EPD material could also benefit manufacturers of HBT-based power amplifiers for cell phones, according to calculations made by Compound Semiconductor.
Although these products contain far fewer HBTs, the emitter area of each transistor is much larger. This means that a typical GSM output stage has a probability of infant failure of 83% when built on a liquid-encapsulated Czochralski substrate (EPD of 45,000 cm-2), but only a 15% chance of failure on a vertical-gradient freeze equivalent (EPD of 4,000 cm-2).
Tom Low s study is described in the article "Agilent proves that defects kill HBTs", which can be found in the August edition of Compound Semiconductor magazine.
