Epitaxial growth

Epitaxy of GaN materials on SiC or Si substrates by metal oxide chemical vapour deposition (MOCVD) or molecular beam epitaxy (MBE).

Device Isolation

Device isolation is achieved by ion implantation or by making steps (removing the channel layer). Isolation between RF devices is a fundamental requirement for making RF circuits.

Ohm contact

Forming ohmic contacts means making the electrodes for the source and drain. For GaN materials, the fabrication of ohmic contacts needs to be done at very high temperatures.

Nitride passivation

After the source and drain have been fabricated, the GaN semiconductor material undergoes a passivation process to remove interfacial states such as hanging bonds, etc. The passivation process for GaN is usually carried out using SiN (silicon nitride).

Gate fabrication

An opening is made in the SiN passivation layer and the gate metal is then deposited. At this point, the structure of the basic field effect transistor is shaped.

Field board production

After the gate is fabricated, additional layers of metal and nitride continue to be deposited to fabricate the field plates, interconnects and capacitors, in addition to protecting the device from the external environment.

Backing thinning

The substrate thickness is thinned to around 100μm and the back of the thinned substrate is then metallised.

Backing through-hole

Through-holes are short channels etched between the upper and lower surfaces of the substrate to reduce the inductance between the device and ground (the bottom metallisation layer).

Origin：www.qorvo.com