Multi-step via etching method

Abstract

The application provides a multi-step via hole etching method, which comprises the following steps: forming photoresist on a semiconductor substrate with a multi-step structure and patterning to form an opening; performing main etching along the opening and stopping at a stop layer; removing the photoresist; forming plasma by using etching gas to etch to perforate the stop layer, a medium layer and a high-K medium layer and stop at a metal plate layer; and performing etching post-processing to reduce polymer accumulation in the via hole by using a processing gas. By introducing low-power soft etching and a specific gas combination, the application can ensure that the via holes with different step depths can smoothly perforate the high-K medium layer and accurately stop at the plate, while minimizing the loss of the ultra-thin metal plate, effectively removing the polymer in the hole, expanding the process window and improving the device yield.

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