Semiconductor Contact Plug via Dual Stop Layers

The patent divides the single etching process into four separate photo-etching processes, each forming openings in different dielectric layers independently. This segmentation prevents direct penetration of contact plugs through metal gates by controlling each etching step to stop at appropriate stop layers, thereby improving device performance while managing fabrication complexity through systematic process division.

The patent introduces stop layers (first and second stop layers) before forming the contact plugs. These stop layers are prepared in advance to control the etching depth and prevent over-etching that would cause direct penetration. By performing this preliminary action of creating depth control structures, the patent ensures reliable device performance while maintaining a manageable fabrication process.

The patent segments the contact plug formation into four distinct photo-etching processes, each targeting a specific dielectric layer with its own mask and etching parameters. This segmentation achieves precise contact plug positioning by controlling each etching step independently with appropriate stop layers, while the modular nature of segmented processes makes the increased complexity manageable through systematic organization.

The patent uses stop layers as intermediary structures between the metal gate and the contact plugs. These stop layers act as mediators that control the etching process, ensuring that contact plugs are formed with precise positioning without directly penetrating the metal gate. The intermediary stop layers absorb the complexity of depth control, allowing precise positioning to be achieved while maintaining a structured fabrication process.