Semiconductor Memory Device Layered Interconnect Alignment

The patent divides the interconnect structure into multiple segments: first and second conductive layers for bit lines, third and fourth conductive layers for word lines, and intermediate layers separating them. This segmentation allows each layer to be formed and aligned independently, improving overall alignment precision while maintaining high integration density through the layered cross-point architecture.

The patent transitions from planar interconnect arrangement to a three-dimensional layered structure. Conductive layers are stacked in multiple levels with intermediate layers, allowing bit lines and word lines to cross in different planes. This dimensional change enables higher integration density without compromising alignment precision, as each layer can be precisely formed and aligned independently before stacking.

The interconnect structure is segmented into distinct conductive layers (first, second, third, fourth) separated by intermediate layers. This segmentation creates well-defined contact interfaces between layers, improving contact formation stability. Each conductive layer can be independently patterned and connected, reducing alignment errors and contact defects while maintaining high integration density through the compact cross-point architecture.

Intermediate layers are introduced as mediator structures between the bit line conductive layers and word line conductive layers. These intermediate layers provide stable contact interfaces and facilitate reliable electrical connections between the crossing conductive lines. The intermediate layers act as buffers that improve contact formation stability and reduce variability in the narrow pitch interconnect structure.

The patent uses a multi-layer three-dimensional interconnect structure where bit lines and word lines cross in different planes. The first and second conductive layers (bit lines) are separated from third and fourth conductive layers (word lines) by intermediate layers, creating short vertical distances between connected elements. This dimensional arrangement reduces the distance from bit lines to lower layer interconnects, improving device operation stability while the systematic layering manages the increased structural complexity.

The interconnect structure employs a nested layered architecture where intermediate layers are positioned between conductive layers, and conductive layers are stacked in a nested sequence. This nesting approach compactly organizes multiple interconnect layers in close proximity, reducing overall device height and the distance between functional elements. The nested structure improves operation stability by minimizing interconnect lengths while systematically managing the complexity through a regular repeating pattern.