Non-thermal alloyed ohmic contact process of GaN-based HEMTs by pulsed laser annealing

Abstract

We have demonstrated Si implantation incorporation into GaN HEMTs with a non-alloyed ohmic contact process. We optimized the power density of pulsed laser annealing to activate implanted Si dopants without a thermal metallization process. The experimental results show that the GaN surface will be reformed under the high power density of the illumination conditions. It provides a smooth surface for following contact engineering and leads to comparable contact resistance. The transmission line model (TLM) measurement shows a lower contact resistance to 6.8×10 −7 Ω•cm 2 via non-alloyed contact technology with significantly improved surface morphology of the contact metals. DC measurement of HEMTs shows better current and onresistance. The on-resistance could be decreased from 2.18 to 1.74 mΩ-cm 2 as we produce a lower contact resistance. Pulsed laser annealing also results in lower gate leakage and smaller dispersion under a pulse I-V measurement, which implies that the density of the surface state is improved.

The Evolution of Manufacturing Technology for GaN Electronic Devices

“…The power density of the pulsed laser annealing is optimized to activate the Si ion-implanted GaN, and then the Ti/Al/Ni/Au ohmic is annealed at 500 °C to form an ohmic contact. Experimental results show that a smooth surface can be obtained and results in a comparable contact resistance; the contact resistivity of a wafer processed using ion implantation/laser annealing technology is shown in Figure 16 [ 86 ].…”

“… ( a ) The contact resistance of implanted sample pulsed laser annealing shows a low contact resistance of 6.84 × 10 −7 Ω cm 2 . ( b ) The contact resistance under different power densities of pulsed laser annealing [ 86 ]. (Data from [ 86 ]).…”

“…( b ) The contact resistance under different power densities of pulsed laser annealing [ 86 ]. (Data from [ 86 ]).…”

Mechanism of Ti/Al/Ni/Au ohmic contacts to AlGaN/GaN heterostructures via laser annealing

“…In the past few years, LA is used in the GaN-on-Si ohmic contact process. [21,22] However, it is more suitable for the GaN-on-SiC ohmic contact process. Because the energy band gaps of Al 0.25 Ga 0.75 N barrier layer (3.9 eV), GaN channel layer (3.4 eV), and SiC substrate (3.25 eV) are all larger than the photon energy of the laser with a wavelength of 532 nm (2.33 eV), the wafer will not absorb the laser energy.…”

Использование импульсного лазерного отжига для формирования омических контактов Mo/Ti к алмазу

“…Это очень быстрый процесс, при котором кислород не успевает диффундировать в контактную систему даже при отжиге в нормальных атмосферных условиях. В работе [9] лазерный отжиг использовался для формирования омических контактов с пониженным контактным сопротивлением к другому широкозонному материалу -GaN. Для алмазов лазерный отжиг использовался в технологиях лазерной резки и гравировки, а также с целью непосредственного создания графитовых контактов в результате графитизации алмаза [10].…”