Segregated Power-Ground Pad Stacks to Prevent RDL Shorting

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Solution Overview

Problem

High-performance computing applications face issues with electrical shorting between power and ground lines during manufacturing, particularly in the lower redistribution layers of high-performance computing packages, which can lead to device failure due to overlapping power and ground pads.

Innovation Solution

A segregated power and ground design is implemented, where power and ground pad stacks are formed as discrete, non-overlapping entities in the lower redistribution layers to prevent electrical shorting, while the upper redistribution layers are used for lateral power routing without forming discrete power pad stacks, thus minimizing the risk of shorting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If power and ground pads are placed in the lower redistribution layers, then power routing capability is improved, but electrical shorting between power and ground lines increases

Engineering Contradiction:

Improvepower routing capabilityVSAvoidelectrical shorting risk

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent divides the lower redistribution layers into separate power pad stacks and ground pad stacks that are spatially segregated and do not overlap. This segmentation prevents electrical shorting between power and ground lines while maintaining effective power routing capabilities through dedicated power delivery paths.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies different design rules to different regions of the lower redistribution layers. Power pad stacks and ground pad stacks are assigned to specific non-overlapping regions, with each region optimized for its specific function. This local differentiation allows effective power routing in power regions while preventing shorting in ground regions.

Inventive Principle:

Principle #3Local quality

2Reliability

If discrete power pad stacks and ground pad stacks are formed in lower redistribution layers, then electrical shorting is prevented, but manufacturing complexity increases

Engineering Contradiction:

Improveelectrical shorting preventionVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments power and ground functions into separate pad stacks in the lower redistribution layers. While this creates distinct power and ground regions, the segmentation is achieved through standard semiconductor manufacturing processes, avoiding excessive complexity by using established fabrication techniques.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent resolves the shorting issue by utilizing the vertical dimension and lateral positioning to create non-overlapping power and ground pad stacks. This spatial arrangement in multiple dimensions allows prevention of electrical shorting while maintaining a relatively simple manufacturing process that follows conventional layer formation techniques.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Ease of manufacture

If overlapping power and ground pads are used in lower redistribution layers, then manufacturing process is simplified, but electrical shorting occurs leading to device failure

Engineering Contradiction:

Improvemanufacturing process simplicityVSAvoiddevice failure rate

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent takes preliminary action by designing non-overlapping power and ground pad stacks before manufacturing begins. This preventive design approach eliminates the risk of electrical shorting and device failure that would otherwise require complex post-manufacturing testing and repair processes, actually simplifying the overall manufacturing workflow by preventing defects upfront.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The patent applies specific design rules to local regions of the lower redistribution layers, assigning power pads to certain areas and ground pads to other areas. This local quality differentiation prevents overlapping and electrical shorting while maintaining a straightforward manufacturing process that follows conventional fabrication steps.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS11804443B2Segregated power and ground design for yield improvement

Publication Date: 2023.10.31 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A method includes encapsulating a plurality of package components in an encapsulant, and forming a first plurality of redistribution layers over and electrically coupling to the plurality of package components. The first plurality of redistribution layers have a plurality of power/ground pad stacks, with each of the plurality of power/ground pad stacks having a pad in each of the first plurality of redistribution layers. The plurality of power/ground pad stacks include a plurality of power pad stacks, and a plurality of ground pad stacks. At least one second redistribution layer is formed over the first plurality of redistribution layers. The second redistribution layer(s) include power lines and electrical grounding lines electrically connecting to the plurality of power/ground pad stacks.