Nitronex teardown shows thermal influence
Those looking to exploit the availability and comparatively low cost of Nitronex s GaN transistors should pay great attention to the chips thermal management measures.
That s the upshot of the teardown of two Nitronex GaN-on-silicon HEMTs by Canadian laboratory MuAnalysis, published on October 17.
“It s easy to break these transistors, not with high currents, but by affecting their heat management,” Martine Simard-Normandin, president and CEO of MuAnalysis told compoundsemiconductor.net.
The Ottawa company has performed teardowns on plastic-packaged 5 W, 3 GHz and 18 W, 3.5 GHz HEMTs, which they purchased for $10 and $40 respectively.
It discovered that the comparatively low thermal conductivity silicon substrate features through-silicon-vias covered with silver-filled epoxy adhesive on the transistor backside. Such thermally conductive metal-filled epoxies are used to help transport heat away from critical temperature-sensitive components.
MuAnalysis also performed emission microscopy on the GaN HEMTs under normal operation, and observed photoluminescent spots coming from the device.
The emission was often brightest from the source side of the device, which Simard-Normandin suggests is simply due to higher current levels passing through this region. Light emission is a clear indication of energy being lost from the RF signal ultimately produced from the transistor.
Other information gleaned by MuAnalysis in its teardowns includes exact chip dimensions, details of metallization schemes and packaging used and how the chips terminals are addressed.
MuAnalysis primary occupation is performing reliability testing and failure analysis under contract to chip manufacturers, and it is now expanding its repertoire from silicon to include compound semiconductors.
“We ve decided to create a little bit of a niche for ourselves in GaN,” Simard-Normandin said. She sees teardowns as a way of increasing the company's knowledge of GaN technology.
Prior to the Nitronex teardowns, MuAnalysis had performed teardowns on LEDs from Cree, Osram and Philips Lumileds.
“We re aware of companies trying to develop GaN products,” explained Simard-Normandin. “These companies will need a laboratory like us to do their qualification.”
“We decided to try and get ahead of the game and determine their breakdown mechanisms.”
