SiC Substrate Strained-Layer Thinning to Reduce Material Loss

The patent applies preliminary action by performing strained layer thinning through controlled cracking and removal before the final CMP step. The strained layer is selectively removed by applying stress to induce cracking at the strained layer interface, allowing removal of the damaged layer while preserving the underlying single crystal structure. This preliminary removal reduces the depth that subsequent CMP must process, significantly reducing material loss while still achieving epi-ready surface quality.

The patent extracts the strained layer from the substrate by inducing controlled cracking. A cracking layer is formed on the substrate surface, and stress is applied to cause the strained layer to crack and separate from the single crystal layer beneath it. This extracted strained layer can then be removed separately, allowing the CMP process to work only on the remaining thin damaged layer rather than removing tens to hundreds of micrometers of valuable single crystal material.

The patent performs preliminary action by removing the bulk of the strained layer through controlled cracking and mechanical separation before applying CMP. The cracking layer is formed and stress is applied to cause the strained layer to crack and detach, allowing removal of most of the damaged material in a relatively short time. This reduces the strained layer depth from tens to hundreds of micrometers down to a thin residual layer that can be quickly polished away, reducing total processing time from several hours to a fraction of that time.

The patent replaces the purely mechanical CMP process with a combination of mechanical cracking and chemical bonding techniques. Instead of relying solely on mechanical abrasion to remove the deep strained layer, the method uses controlled stress application to induce cracking and separation, followed by selective removal. This hybrid approach is much faster than conventional CMP alone while still achieving the required surface quality for epitaxial growth.

The patent extracts the strained layer by forming a cracking layer on the substrate surface and applying stress to cause the strained layer to crack and separate from the single crystal layer. This extracted strained layer is then removed, allowing elimination of the subsurface damaged layer while preserving the valuable single crystal material beneath. This reduces material loss from tens to hundreds of micrometers to just the thin residual strained layer, dramatically reducing the cost of material loss.

The patent performs preliminary removal of the strained layer through controlled cracking and mechanical separation before final CMP polishing. By removing the bulk of the damaged material in advance through this selective process, the subsequent CMP step only needs to remove a thin residual layer, significantly reducing the total amount of valuable single crystal material that must be discarded while still achieving complete elimination of the subsurface damaged layer.