Stacked Memory Die Wire Bonding to Prevent Sagging Shorts
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Solution Overview
Problem
As the number of memory dies in a stack increases, the length of wires coupling them to a control circuit also increases, leading to wire sagging and potential shorting due to slack or weight, which can limit the storage capacity and functionality of the memory system.
Innovation Solution
Bonding neighboring wires together using an adhesive to increase the gap between them, thereby preventing shorting and allowing for larger stacks of memory dies without compromising functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If additional memory dies are included in the stack to increase storage capacity, then the storage capacity of the memory system is improved, but the wire length increases leading to wire sagging and potential shorting
Solution Approach 1:
The patent introduces a vertical dimension by bonding wires to the substrate at multiple heights. Instead of keeping all wires in a single horizontal plane, wires are bonded at different vertical positions, creating a three-dimensional wire routing structure. This dimensional change allows wires to be positioned above or below each other, preventing horizontal overlap and potential shorting while accommodating longer wire routes for additional memory dies in the stack.
Solution Approach 2:
The wire routing is segmented into multiple bonding locations at different heights rather than using a single bonding plane. Wires are divided into segments that are bonded to the substrate at intermediate points along their length, creating multiple support points at different vertical levels. This segmentation prevents wire sagging by providing structural support at multiple heights and eliminates shorting risks by separating wire paths vertically.
2Quantity of substance
If wire length is increased to accommodate more memory dies in the stack, then the storage capacity is improved, but wire sagging occurs due to increased slack or weight
Solution Approach 1:
Wires are bonded to the substrate at intermediate locations before the complete wire routing is finalized. These preliminary bonding points are established at different heights to preemptively support the wire against gravitational sagging. By securing wires at multiple vertical levels in advance, the structure prevents sagging from occurring as the wire length increases to accommodate additional memory dies in the stack.
Solution Approach 2:
The bonding structure transitions from a two-dimensional horizontal bonding plane to a three-dimensional multi-level bonding architecture. Wires are bonded at various heights above the substrate, creating vertical separation between wire segments. This dimensional change allows long wires to be supported at multiple vertical levels, preventing sagging while maintaining the necessary wire length for connecting to additional memory dies.
3Reliability
If multiple wires are bonded together to increase gaps and prevent shorting, then the reliability is improved, but the device complexity increases
Solution Approach 1:
Multiple wires are bonded together at shared bonding locations on the substrate. Instead of treating each wire as a separate entity requiring individual routing, wires are merged into bundles that are bonded collectively at intermediate points. This merging approach prevents shorting by maintaining proper spacing between wire bundles while reducing the overall complexity compared to routing each wire separately through the entire length.
Solution Approach 2:
Wire bonding is extended into the vertical dimension with bonds formed at multiple heights. Wires are bonded to the substrate at different vertical levels rather than all at the same plane. This multi-level bonding structure naturally separates wires vertically, preventing shorting through horizontal proximity while organizing the complex wire routing into manageable vertical layers, thereby reducing overall system complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces the risk of wire shorting, enabling the inclusion of more memory dies in the stack while maintaining proper operation and increasing storage capacity.
Implementation Method 1
Bonding neighboring wires together using an adhesive to increase the gap between them
Data Source
AI summary
Methods, systems, and devices for wire bonding for stacked memory dies are described. A memory system may include a stack of memory dies. As the stack grows to include more and more memory dies, the length of the wires coupling the memory dies with the control circuit may increase. Bonding multiple wires using an adhesive may increase a gap between neighboring wires coupled with the same memory die or different memory dies. For example, bonding one wire to a neighboring wire may pull one or both of the bonded wires away from their original placement, increasing a gap between the bonded wires and one or more neighboring wires. Bonding the wires coupled with a lower memory die may increase a gap such that sagging wires coupled with an upper memory die may be positioned in the gap to avoid shorting with the lower wires.