Materials Science Forum Vol. 1193

Abstract: Electrochemical etching (ECE) of silicon carbide is a powerful route to porous 4H‑SiC. Yet, reliable pore initiation on the Si-face typically requires additional sophisticated pre-conditioning (e.g. masked KOH etching, metal-assisted photochemical etching (MAPCE), focused ion beam (FIB) milling), limiting industrial adoption. We demonstrate a simple, CMOS‑compatible pre‑conditioning based on short reactive‑ion‑etching (RIE) steps (10–30 s, SF₆/O₂) that reproducibly nucleate pores on the Si‑face of highly doped 4H‑SiC (resistivity < 0.02 Ω·cm) and enable homogeneous ECE in HF/ethanol without UV illumination. Surface roughness increases modestly with RIE time (R_a ≈ 1.3 nm to 4.0 nm), while subsequent ECE does not significantly degrade topography. SEM cross‑sections reveal continuous porous layers; image‑based quantification shows enhanced vertical pore alignment with longer RIE duration. A stepwise voltage program (11.5 V → 8.5 V → 11.5 V) yields stable current transients during etching. Eliminating noble metals and lithography reduces contamination risk. It improves process compatibility with front‑end manufacturing while remaining synergistic with our previously established ECE process flows and high‑temperature reorganisation of thin, porous SiC layers.

Abstract: Silicon carbide (SiC) wafers are essential for next-generation power devices, however conventional dicing methods often induce cracks and Basal Plane Dislocations (BPDs), reducing device reliability. This study demonstrates BPD-free dicing of epitaxial SiC wafers using Water jet Guided Laser (WGL) processing. Full-thickness cutting was performed on 350 μm-thickness wafers with a 10 μm-thickness epitaxial layer using a YAG laser (532 nm wavelength, 200 ns pulse width, 10 kHz repetition rate, 30–80 W output) on an LB300 system. BPD evaluation was carried out by X-ray topography (XRT) with the-1-128 reflection before and after cutting. The results showed no generation or propagation of new BPDs, and pre-existing BPDs did not glide, confirming that WGL processing enables BPD-free machining. These results are attributed to the ablation-based nature of WGL with water assistance, which avoids mechanical stress on epitaxial SiC wafers.

Abstract: This study aims to develop an electrochemical assisted fixed-abrasive lapping (ECAL) process for thinning 4H-SiC wafers (C-face). Process with 20 wt% NaNO₃ electrolyte to generate a softened passivation layer has been formed and simultaneously removed by a fixed diamond lap wheel. Electrochemical tests using a potentiostat have verified 20 V as the selected experimental potential, and a significant reduction in hardness has been confirmed by nanoindentation. Under these conditions, the 4-inch wafer has achieved a material removal rate (MRR) of 3.181 μm/h with wafer quality (Bow –7.80 μm, Warp 48.50 μm, TTV 7.70 μm). When the same conditions have been applied to 6-inch wafers, an MRR of 2.457 μm/h and wafer quality (Bow –5.00 μm, Warp 36.70 μm, TTV 6.60 μm) have been obtained. These results have demonstrated the scalability of ECAL for larger SiC substrates, offering potential for next-generation device manufacturing.