Comparison of Solid-State Microwave Annealing with Conventional Furnace Annealing of Ion-Implanted SiC

Abstract

Rapid solid-state microwave annealing was performed for the first time on N + -, Al + -, and B + -implanted SiC, and the results were compared with the conventional furnace annealing. For microwave annealing, temperatures up to 2,000°C were attained with heating rates exceeding 600°C/s. An 1,850°C/35 s microwave anneal yielded a root-mean-square (RMS) surface roughness of 2 nm, which is lower than the 6 nm obtained for 1,500°C/15 min conventional furnace annealing. For the Al implants, a minimum room-temperature sheet resistance (R s ) of 7 kW/h was measured upon microwave annealing. For the microwave annealing, Rutherford backscattering (RBS) measurements indicated a better structural quality, and secondary-ion-mass-spectrometry (SIMS) boron implant depth profiles showed reduced boron redistribution compared to the corresponding results of the furnace annealing.

High-Dose Phosphorus-Implanted 4H-SiC: Microwave and Conventional Post-Implantation Annealing at Temperatures ≥1700°C

“…Microwaves ($1 GHz) from a source can be amplified and directly coupled to a SiC sample to be annealed through a microwave heating head. [6][7][8] Since the sample is placed in microwave-transparent surroundings, the microwaves are absorbed by the SiC sample only, leading to extremely high heating and cooling rates. This feature contrasts microwave annealing with resistive and inductive heating furnaces, where the heating source heats not only the sample but also the surrounding ambient.…”

“…Attractive electrical activation and lattice perfection after microwave annealing of ion-implanted SiC have already been published. 6,9,10 Phosphorus (P) is the preferred donor (n-type) impurity in SiC at elevated doping concentrations because of its higher electrical activation with respect to nitrogen (N). [11][12][13][14] In 4H-SiC for implanted P concentration up to 10 20 cm À3 , almost complete electrical activation 14 and implanted layer resistivity as low as 2 9 10 À3 X cm to 3 9 10 À3 X cm at Room Temperature (RT) have been reported for conventional annealing at 1700°C.…”

Solid-state microwave annealing of ion-implanted 4H–SiC

“…Clearly, these values are too high for fabricating efficient SiC power devices [8]. Recently, we started investigating the use of a novel solid-state microwave technique for annealing ion-implanted SiC [9]. The microwave processing system is capable of providing a temperature rise rate of 600°C/s and a fall rate of 400°C/s, enabling short duration high-temperature (>1800°C) annealing.…”

“…, respectively. A detailed description of the solid-state microwave annealing system used in this study is provided elsewhere [9]. The annealing temperatures in this study ranged from 1750°C to 2120°C for the aluminum implanted samples and 1700-1950°C for the phosphorus implanted samples.…”

“…However, these latter gases were found to ionize (generating arcing) due to the intense microwave field in the vicinity of the SiC sample. The samples annealed in open air resulted in thick oxide layers [9].…”