Hybrid Bond Wire Diameters for Memory Die IR Drop Control
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Solution Overview
Problem
As design rules shrink, memory devices face issues with power signal integrity (PSI) failure due to IR drop, which affects circuit timing and functionality, particularly in smaller die sizes.
Innovation Solution
Implementing a hybrid wire size diameter under a single memory die, where power pads have a larger bonding wire diameter (e.g., 1.0 mm) and signal pads have a smaller diameter (e.g., 0.7 mm) to reduce IR drop while maintaining a small die size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If design rules are shrunk to reduce die size, then die size is reduced, but power signal integrity deteriorates due to IR drop
Solution Approach 1:
The patent applies different wire diameters to different functional areas of the die: power pads use larger diameter wires (2 mil) to minimize IR drop, while signal pads use smaller diameter wires (1.5 mil) to maintain timing integrity. This local differentiation resolves the contradiction by optimizing each area's wire size according to its specific electrical requirements rather than using a uniform size across the entire die.
2Ease of manufacture
If uniform wire size is used across all pads, then manufacturing is simplified, but power signal integrity fails due to IR drop
Solution Approach 1:
The patent implements local quality by specifying different wire diameters for power pads versus signal pads. Power pads receive 2 mil wires to reduce IR drop, while signal pads use 1.5 mil wires. This resolves the contradiction between manufacturing simplicity and power signal integrity by creating a targeted differentiation that addresses only the power delivery issue without complicating the overall bonding process.
3Reliability
If larger wire diameter is used for power pads, then IR drop is reduced, but die size increases
Solution Approach 1:
The patent applies larger diameter wires (2 mil) specifically to power pads where IR drop is critical, while using smaller wires (1.5 mil) for signal pads. This localized approach reduces IR drop in the power delivery path without requiring all wires across the die to be larger, thereby maintaining compact die size while achieving improved power signal integrity where it matters most.
Solution Approach 2:
The patent segments the wire bonding system into two distinct categories: power pad wires and signal pad wires. This segmentation allows each type to be optimized independently for its specific function, with power wires sized for low IR drop and signal wires sized for timing performance, without forcing a one-size-fits-all approach that would increase overall die size.
4Productivity
If smaller die size is implemented, then device density increases, but wire bond shorting risk increases
Solution Approach 1:
The patent uses different wire diameters for power and signal pads to create physical differentiation that reduces shorting risk. The 2 mil power wires and 1.5 mil signal wires have distinct characteristics that make accidental shorting less likely, even in compact die layouts where pads are closely spaced. This local differentiation maintains device density while improving reliability.
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 improves IR drop and reduces the risk of wire bond shorting, allowing for desired performance with a smaller die size and maintaining signal integrity.
Implementation Method 1
each bonding wire coupled to a respective one of the plurality of power pads can have a second wire size diameter larger than the first wire size diameter... can improve IR drop
Implementation Method 2
each bonding wire coupled to a respective one of the plurality of signal pads can have a first wire size diameter... can maintain signal integrity
Data Source
AI summary
Systems and apparatus are provided for a hybrid wire size diameter under one single die. For example, an apparatus can include a memory cell die, a plurality of signal pads under the memory cell die and a plurality of power pads under the memory cell die. Each bonding wire coupled to a respective one of the plurality of signal pads has a first wire size diameter and each bonding wire coupled to a respective one of the plurality of power pads has a second wire size diameter larger than the first wire size diameter.