We have introduced a unique patented approach to achieve low damage and high-quality SiC substrate polishing on our 200 mm production platform. Plasma polish has been proven to produce a damage-free surface and subsurface ideally suited for high yielding 150 mm epitaxial growth.

The SiC substrate surface quality is the starting point affecting the quality of epi, device performance, reliability and lifetime. Achieving an optimal surface is difficult due to the hardness of SiC and the methods used to slice and thin the wafers from the starting boule. Properly conditioning the surface is vital to enable yield and performance down the manufacturing line.

Plasma polish dry etching is an established processing technique within front end processing for semiconductor high volume manufacturing. Oxford Instruments has developed and patented processes and equipment adaptions, providing a comprehensive silicon carbide polishing solution and delivering the surface material quality required for SiC high volume production.

SiC substrate surface before polishing

Figure 1. AFM image: unpolished substrate (Ra = 1.5 nm).

SiC substrate surface after etch

Figure 2. AFM image: after plasma polish (Ra = 0.70 nm).

SiC substrate surface after epi growth

Figure 3. AFM image: SiC epi-layer on plasma polish wafer (Ra = 0.14 nm).

Using slurry components for the chemical mechanical processing can significantly increase the operational expenses. PPDE offers a very attractive lower opex and cleaner alternative to a costly and toxic chemicals intensive CMP process while approaching near zero wafer breakage levels

Oxford Instruments' plasma polish dry etch process enables thinner slicing industry roadmap to achieve increased wafers/boule further supporting the desired industry cost-down roadmap.