4inch -SICOI wafers Dopant Selective Photoelectrochemical Etching of SiC

Paper Download

Dopant Selective Photoelectrochemical Etching of SiC.pdf

OMedaSemi develop 4-6 inch SICOI wafers (silicon carbide on insulator wafers). The wafers use Direct Bonding(hydropholic bonding) or surface activated bonding technology to bond thermal oxide wafers and 4H high-purity semi-insulating silicon carbide wafers together, and then control the thickness to the thickness you need through ion implantation, annealing, thinning or direct thinning and CMP polishing. It is worth noting that ion implantation and direct CMP and thinning have their own advantages and disadvantages.

Summary:

The study explores a novel method for precisely fabricating silicon carbide (SiC) thin films using dopant-selective photoelectrochemical (PEC) etching, critical for future MEMS and quantum photonic devices. SiC, particularly 4H-SiC, offers excellent properties for quantum and nonlinear optical applications, but conventional etching techniques struggle with achieving uniform, defect-free, thin films.

The authors demonstrate that PEC etching under UV light allows for high selectivity between doped layers (n-type vs. p-type), enabling the use of doped layers as etch-stops to control film thickness precisely. They achieve:

• High dopant selectivity (>20:1 in one step; up to 180:1 across two layers),

• Fast etch rates (>4 µm/hour),

• Low surface roughness (~1 nm RMS),

• Significant reduction in thickness variation (TTV)—from ~180 nm down to ~1 nm with two etch stops.

This scalable approach allows wafer-scale fabrication of SiC-on-insulator structures with nanometer precision, essential for integrating SiC into advanced photonic and quantum devices.