14nm FinFET

The "Stop Oxide Deposition" step acts as a critical etch-stop and protection layer positioned between the underlying Pad Nitride and the subsequent amorphous Silicon (a-Si) hardmask layer used for fin patterning [P1][P2]. In advanced multi-patterning schemes like self-aligned double patterning (SADP), the a-Si layer acts as a sacrificial mandrel which must be selectively etched using anisotropic plasma processes [P1][P2]. Without this Stop Oxide, the halogen-based chemistry used to pattern the a…

• [High] Under-Etch or Etch-Punchthrough of the Stop Layer: If the deposited stop oxide film possesses poor density or non-uniform thickness, the subsequent anisotropic a-Si mandrel etch may prematurely punch through the oxide layer, leading to unwanted consumption of the underlying pad nitride and pad oxide layers [P1][T3]. This punch-through is driven by a lack of chemical etch resistance, often caused by excessive hydrogen incorporation and low network density during low-temperature depos…