Laser Direct Write and Gas Immersion Laser Doping Fabrication of SiC Diodes

Abstract

Laboratory prototype SiC diodes are fabricated using a combination of gas immersion laser doping (GILD) and laser direct write (LDW) in situ metallization in a commercial SiC wafer. Trimethylaluminum (TMA) and nitrogen are the precursors used to produce p-type and n-type SiC, respectively. Using these techniques, a 150 nm p-type doped junction is fabricated in semiinsulating 6H-SiC and n-doped 4H-SiC wafers. Ohmic contacts are created by laser direct metallization producing carbon rich conductive phases in these doped materials. Alternatively an excimer laser can be used to create silicon rich Schottky contacts. The geometry of the diodes can be vertical or planar to the wafer surface and the laser processes are thought to reduce defect densities in the irradiated areas. These laser-processed diodes are intended for use in high temperature, high voltage and high frequency switching and sensing applications.

Characteristics of 6H-silicon carbide PIN diodes prototyping by laser doping

“…The current-voltage (I-V) and capacitance-voltage (C-V) characteristics of the PIN diodes were measured by using micromanipulators connected to a Tektronix 576 curve tracer (Beaverton, OR) and to an HP-4284A LCR multimeter (Palo Alto, CA), respectively. No wire bonding was used for electrical contacts for the I-V and C-V measurements because laser direct write allows metallization by phase transformation without any metal deposition to produce both Schottky and Ohmic contacts, [16][17][18]21,22 which were contacted directly by the microprobes of the I-V and C-V measurement instruments.…”

Fabrication of Silicon Carbide PIN Diodes by Laser Doping and Planar Edge Termination by Laser Metallization

“…No wire bonding was used for electrical contacts for the I-V measurements because laser direct write allows metallization by phase transformation without any metal deposition to produce both Schottky and Ohmic contacts [4][5][6][7] which were contacted directly by the microprobes of the I-V measurement instruments. Dopant depth profiles were obtained using secondary ion mass spectroscopy (SIMS).…”

“…A laser conversion technology, first reported by Quick [3] was investigated [1,[4][5][6][7][8][9] to laser direct metallize without metal deposition and laser dope in SiC without high temperature annealing, as an alternative to the conventional ion implantation, and fabricate Schottky diodes and PIN diodes on 4H-and 6H-SiC wafers. This paper presents experimental results on the improved performance of PIN diodes fabricated by laser doping using three methods; reducing the active area of the diode, annealing and edge termination by laser metallization.…”