Offset Die Stacking in Multi-Chip Packages
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Solution Overview
Problem
Current Multi-Chip Packages (MCPs) face limitations in storage capacity, manufacturing complexity, and cost due to interconnect congestion, overhanging dice, and the need for multiple assembly steps, especially when stacking semiconductor dice with varying bonding pad orientations.
Innovation Solution
The solution involves stacking multiple identical semiconductor dice on a substrate with bonding pads oriented in opposite directions, allowing for lateral offsetting to prevent overhanging and enable all bond wires to be attached in a single step, reducing interconnect density and manufacturing complexity while allowing for thinner dice and increased storage capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If interposers are used to provide clearance for bond wire attachment, then bond wire attachment is enabled, but the thickness of interposers limits the number of dice that can be stacked
Solution Approach 1:
The patent removes the interposer component entirely from the MCP structure. Instead of using interposers to provide clearance, the dice are laterally offset relative to each other, allowing bond wires to be attached directly from the substrate to bonding pads on upper dice without requiring additional clearance-providing components.
Solution Approach 2:
The patent introduces lateral offsetting between dice in the horizontal plane rather than relying on vertical clearance provided by interposer thickness. This dimensional approach allows bond wires to clear underlying dice structures by positioning bonding pads laterally away from overhanging dice, enabling taller stacks within the same package height.
2Productivity
If dice are stacked with bonding pads on opposite sides, then all bond wires can be attached in a single step, but interconnect congestion occurs on the substrate
Solution Approach 1:
The patent employs asymmetric lateral offsetting where dice are offset in alternating directions (left-right, right-left) rather than symmetric offsetting. This asymmetric arrangement distributes bond wires across different lateral zones on the substrate, preventing congestion and routing conflicts that would occur with symmetric arrangements where all bonding pads face the same direction.
Solution Approach 2:
The patent segments the bond wire connections into distinct lateral groups based on dice orientation. Dice with bonding pads on opposite sides are offset to different lateral positions, effectively segmenting the interconnect space and allowing all bond wires to be routed without congestion, while still enabling single-step attachment of all wires.
3Quantity of substance
If dice are laterally offset to prevent overhanging, then storage capacity increases, but manufacturing complexity increases due to precise positioning requirements
Solution Approach 1:
The patent incorporates lateral offset positioning into the die stacking process itself, rather than requiring separate precision alignment steps. The offset is built into the stacking methodology, allowing standard wire bonding equipment to attach all bond wires in a single step without requiring additional precision positioning operations, thereby reducing manufacturing complexity despite increased storage capacity.
Data Source
AI summary
A semiconductor device has a plurality of stacked semiconductor dice mounted on a substrate. Each die has similar dimensions. Each die has a first plurality of bonding pads arranged along a bonding edge of the die. A first group of the dice are mounted to the substrate with the bonding edge oriented in a first direction. A second group of the dice are mounted to the substrate with the bonding edge oriented in a second direction opposite the first direction. Each die is laterally offset in the second direction relative to the remaining dice by a respective lateral offset distance such that the bonding pads of each die are not disposed between the substrate and any portion of the remaining dice in a direction perpendicular to the substrate. A plurality of bonding wires connects the bonding pads to the substrate. A method of manufacturing a semiconductor device is also disclosed.