Staircase Interconnect Flip-Chip Stacking for High-I/O Memory Packaging
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Solution Overview
Problem
As device feature sizes and package sizes approach their limits, creating sufficient input/output (I/O) contacts for planar and 3D memory chips becomes increasingly challenging, especially for 3D NAND memory devices that require a large number of vertical levels and staircase structures, which traditional fan-out packaging technologies struggle to support effectively.
Innovation Solution
The implementation of a semiconductor package with a redistribution layer (RDL) and a staircase interconnect structure that includes stacked staircase layers, where each layer is offset to expose portions of the previous layer, allowing for increased I/O connection points through pillar bumps, enabling efficient electrical connections to integrated circuit chips.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional fan-out packaging technology is used, then manufacturing process is simple, but the number of I/O connection points is insufficient
Solution Approach 1:
The patent transitions from planar 2D packaging to 3D vertical stacking architecture. Multiple memory chips are stacked vertically with interconnect structures extending in the vertical dimension, enabling significantly more I/O connection points by utilizing the third dimension (height) rather than expanding only in the planar area.
Solution Approach 2:
The patent implements nested interconnect structures where conductor patterns are formed within recesses of dielectric layers. The interconnect structure is embedded within the stacked chip architecture, with conductor patterns nested in recesses of dielectric layers, creating a compact nested configuration that maximizes connection density.
2Area of moving object
If device feature size is reduced, then device footprint is reduced, but creating sufficient I/O contacts becomes increasingly challenging
Solution Approach 1:
The patent compensates for reduced planar area by exploiting the vertical dimension. As feature sizes shrink and planar area is reduced, the design uses multiple vertical stacking layers with interconnect structures extending vertically, thereby maintaining sufficient I/O contact capacity despite smaller footprint by transitioning to 3D spatial utilization.
Solution Approach 2:
The patent segments the I/O contact function across multiple vertical levels and layers. Instead of concentrating all I/O contacts in a single planar layer, the design distributes contacts across multiple stacked chips and interconnect layers, with each layer providing a subset of the total I/O capacity, thereby achieving high contact density in reduced footprint through segmentation across vertical space.
Data Source
AI summary
The present disclosure includes a semiconductor package including a redistribution layer (RDL) having a first surface in contact with input/output (I/O) contacts and a second surface opposite to the first surface. The semiconductor package also includes a staircase interconnect structure formed on the second surface of the RDL and electrically connected with the RDL. The staircase interconnect structure includes staircase layers including a first staircase layer and a second staircase layer stacked on a top surface of the first staircase layer. The second staircase layer covers a portion of the top surface of the first staircase layer such that a remaining portion of the top surface of the first staircase layer is exposed. Integrated circuit (IC) chips are electrically connected to the RDL via the staircase interconnect structure. A first IC chip of the IC chips is electrically connected to the RDL.