RDL Staircase Interconnects for Flip-Chip Stack I/O Expansion
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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 with multiple vertical levels, as existing fan-out packaging technologies struggle to support the increasing demand for higher storage capacity.
Innovation Solution
The implementation of a semiconductor package with a redistribution layer (RDL) and a staircase interconnect structure, where each IC chip is electrically connected through pillar bumps formed on each level of the stacked staircase interconnect structure, increasing the number of I/O connection points by forming multiple staircase layers with exposed interconnects for efficient electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If existing fan-out packaging technologies are used, then manufacturing simplicity is maintained, but the number of I/O connection points is insufficient for higher storage capacity
Solution Approach 1:
The patent transitions from planar packaging to three-dimensional stacked packaging, where multiple IC chips are vertically stacked and interconnected through staircase interconnect structures. This dimensional change enables significantly more I/O connection points by utilizing vertical space rather than only horizontal plane, directly resolving the contradiction between connection quantity and structural complexity.
Solution Approach 2:
The staircase interconnect structure implements a nested configuration where multiple interconnect layers are stacked vertically, with each layer providing additional connection points. The structure nests conductive pathways within dielectric layers, creating a compact multi-level interconnect system that increases I/O capacity without proportionally increasing overall package volume.
2Quantity of substance
If device feature size is reduced to increase storage capacity, then storage density is improved, but creating sufficient I/O contacts becomes increasingly challenging
Solution Approach 1:
By moving from two-dimensional planar contacts to three-dimensional stacked contacts, the patent provides additional I/O contact opportunities without further reducing feature sizes. The vertical stacking creates multiple contact layers, effectively multiplying the number of available I/O contacts while maintaining manufacturable feature dimensions.
Solution Approach 2:
The I/O contact structure is segmented into multiple discrete layers and levels within the staircase interconnect architecture. This segmentation allows I/O contacts to be distributed across different vertical levels, reducing the density requirement at any single location and making fabrication more manageable despite increased total contact quantity.
3Quantity of substance
If planar memory chip architecture is used, then fabrication is simpler, but density limitation prevents higher storage capacity
Solution Approach 1:
The patent implements three-dimensional memory architecture by stacking multiple IC chips vertically and creating multi-level staircase interconnect structures. This vertical dimension multiplication dramatically increases memory density compared to planar architectures, as storage capacity scales with the number of stacked layers rather than only lateral chip area.
Solution Approach 2:
The staircase interconnect structure nests multiple conductive pathways within a compact vertical footprint, with each interconnect layer providing additional memory access pathways. This nested configuration enables high-density memory organization without proportionally increasing package volume, resolving the density-versus-complexity contradiction.
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 through the remaining portion of the top surface of the first staircase layer.