Semiconductor Package Substrate Cavity Design for 3DIC

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Solution Overview

Problem

Existing 3DIC packages face challenges such as large form factor, complex heat dissipation requirements, high manufacturing costs, and defects like solder bridges and warpage, particularly in high-density configurations like package-on-package (PoP) and thin substrates, due to lengthy interconnect paths and costly through-substrate vias.

Innovation Solution

A semiconductor package design featuring a die stack with redistribution layers (RDLs) and connectors on one side, allowing for a smaller form factor, reduced conduction paths, and independent heat dissipation features on opposite surfaces, eliminating the need for extensive through-substrate vias and simplifying bonding to a package substrate with a cavity, thereby reducing manufacturing costs and improving reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional through-substrate vias (TSVs) are used to connect dies to package substrate, then electrical connection is achieved, but manufacturing cost increases and conduction path length increases

Engineering Contradiction:

Improveelectrical connectionVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The package substrate is segmented into a cavity region and a build-up portion, with the die stack positioned within the cavity. This segmentation eliminates the need for through-substrate vias by providing direct electrical connection paths through the build-up portion, thereby reducing manufacturing complexity and cost while maintaining reliable electrical connectivity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The build-up portion acts as an intermediary structure between the die stack and the external environment, providing electrical connection paths without requiring through-substrate vias. This intermediary structure simplifies the manufacturing process by eliminating the need to drill and fill holes through the entire substrate thickness.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If high density solder balls are used in package-on-package configurations, then connection density increases, but solder bridges and warpage defects increase

Engineering Contradiction:

Improveconnection densityVSAvoiddefect rate

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The invention transitions from a planar arrangement of solder balls to a three-dimensional structure where the die stack is positioned within a cavity. This dimensional change allows for higher connection density without the solder balls being in direct contact, thereby eliminating solder bridge defects while maintaining high productivity.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Volume of moving object

If thin package substrates are used, then form factor is reduced, but warpage and manufacturing difficulties increase

Engineering Contradiction:

Improveform factorVSAvoidmanufacturing difficulty

Core Design Contradiction:

Volume of moving objectVSEase of manufacture

Solution Approach 1:

The package substrate is segmented into a thin cavity region and a build-up portion with integrated heat dissipation features. This segmentation allows the overall form factor to be reduced while the build-up portion provides sufficient structural support to prevent warpage and manufacturing difficulties associated with uniformly thin substrates.

Inventive Principle:

Principle #1Segmentation

4Temperature

If complex heat dissipation features are integrated into the substrate, then thermal management is improved, but device complexity and manufacturing cost increase

Engineering Contradiction:

Improveheat dissipationVSAvoidsubstrate structure

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The heat dissipation features are merged with the build-up portion of the package substrate, forming an integrated structure. This merging allows thermal management to be achieved without adding separate complex heat dissipation components, thereby improving temperature control while maintaining relatively simple device structure and manufacturing processes.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS9768090B2Substrate design for semiconductor packages and method of forming same

Publication Date: 2017.09.19 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

An embodiment device package includes a package substrate and a first and a second die bonded to the package substrate. The package substrate includes a build-up portion comprising a first contact pad and a plurality of bump pads. The package substrate further includes an organic core attached to the build-up portion, a through-via electrically connected to the first contact pad and extending through the organic core, a second contact pad on the through-via, a connector on the second contact pad, and a cavity extending through the organic core. The cavity exposes the plurality of bump pads, and the first die is disposed on the cavity and is bonded to the plurality of bump pads.