Staggered Semiconductor Die Stacking for Testing Accessibility
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Solution Overview
Problem
Existing stacked-die packaging solutions face limitations in size reduction and testing accessibility, as vertically stacked dies with uniform horizontal encumbrance restrict the number of dies that can be stacked and hinder electrical testing due to covered contact pads.
Innovation Solution
The solution involves staggering semiconductor dies vertically while maintaining horizontal alignment, with exposed contact pads for testing and internal through silicon vias that are obliquely inclined to enhance connection density and accessibility, allowing for improved testing and potential redundancy in electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If dies are vertically stacked with uniform horizontal encumbrance, then space utilization is improved, but testing accessibility deteriorates due to covered contact pads
Solution Approach 1:
The contact pads are segmented into two functional groups: exposed contact pads for testing and covered contact pads for electrical connection. This segmentation allows the testing function to be performed through exposed pads while the covered pads provide electrical connectivity to upper dies, resolving the contradiction between space utilization and testing accessibility.
Solution Approach 2:
Different regions of the die surface are assigned different qualities: some areas have exposed contact pads for testing purposes, while other areas have covered contact pads for electrical connection. This local differentiation enables simultaneous achievement of testing accessibility and compact vertical stacking.
2Length of stationary object
If more dies are stacked vertically, then size reduction is achieved, but testing complexity increases due to limited accessibility
Solution Approach 1:
By segmenting contact pads into exposed and covered types, the invention enables testing of multiple stacked dies through accessible exposed pads, reducing testing complexity despite increased vertical stacking density.
Solution Approach 2:
Exposed contact pads serve as intermediaries that provide access to electrical signals from upper dies without requiring physical access to the top surface of the stacked structure, thereby simplifying testing of multi-die configurations.
3Quantity of substance
If contact pads are covered by overlying dies, then electrical connection density is improved, but measurement capability deteriorates
Solution Approach 1:
Contact pads are divided into covered and exposed categories, where covered pads provide electrical connection density while exposed pads maintain measurement capability. This segmentation allows both requirements to be satisfied simultaneously through functional differentiation.
Data Source
AI summary
An electronic device provided with a package housing a stacked structure formed by dies of semiconductor material, which have a respective integrated circuit and a respective top surface, which extends in a horizontal plane, and are stacked on one another in a vertical direction, transverse to the horizontal plane, and staggered parallel to the same horizontal plane. Provided at a first portion of the top surface is a first plurality of contact pads, and provided at a second portion of the top surface is a second plurality of contact pads. The first portion is covered by a overlying die, and the second portion is exposed and freely accessible. At least some of the contact pads of the first plurality are electrically coupled to internal through silicon vias traversing a substrate of the overlying die to put overlapping dies in electrical contact.