Single Diffusion Break Layout for Higher Active Region Density

The patent changes the width parameter of the diffusion break from being equal to gate width (in conventional approaches) to being less than gate width. This is achieved by forming the diffusion break with specific dimensional constraints (width less than transistor gate width) and extending it deeper into the substrate, thereby reducing the lateral space required while maintaining isolation functionality, which increases active region density.

The patent moves the diffusion break functionality from a primarily lateral (2D) structure to a structure that extends vertically into the substrate. By making the diffusion break extend deeper into the substrate with reduced lateral width, the solution utilizes the vertical dimension to achieve isolation, freeing up lateral space for increased active region density.

The patent performs preliminary actions by forming the diffusion break structure with specific width and depth characteristics before final device assembly. The diffusion break is formed with predetermined dimensions (width less than gate width) and extended into the substrate in advance, establishing precise geometric constraints that guide subsequent manufacturing steps and ensure consistent isolation performance.

The patent employs selective etching processes that utilize plasma chemistry and gas-phase reactions to precisely define the diffusion break geometry. By controlling etch parameters (gas composition, pressure, temperature, power), the manufacturing process achieves high precision in forming the diffusion break width and depth, enabling reduced lateral dimensions while maintaining manufacturing control.