Substrate Channels for Thermal Isolation in Stacked Semiconductor Devices
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Solution Overview
Problem
During the manufacturing of vertically stacked semiconductor devices, heat transfer from bonded die stacks to neighboring stacks can prematurely cure non-conductive film layers, impairing subsequent bond formation and leading to yield loss and reduced reliability.
Innovation Solution
Modifying the substrate by creating channels that reduce or prevent heat transfer between die stacks, such as by thinning, cutting, or removing portions of the substrate to inhibit heat pathways, thereby keeping non-conductive film layers uncured during bonding processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If heat is applied to bond die stacks together, then bonding strength is improved, but heat transfers to neighboring die stacks causing premature curing of non-conductive film layers
Solution Approach 1:
The substrate is divided into isolated regions by creating channels or trenches between adjacent die stacks. This segmentation prevents heat from propagating laterally from one die stack to neighboring stacks, allowing each stack to be bonded independently without thermal interference. The channels act as thermal barriers that segment the heat flow paths.
Solution Approach 2:
The channels or trenches in the substrate serve as intermediary thermal barriers between die stacks. These intermediary structures interrupt the direct heat transfer pathway, allowing heat to be contained within the targeted die stack region while preventing it from reaching adjacent stacks that have not yet been bonded.
2Productivity
If multiple die stacks are bonded simultaneously, then productivity is improved, but heat transfer between stacks causes premature heating and yield loss
Solution Approach 1:
By creating thermal isolation channels between die stacks, the substrate is segmented into independent bonding zones. This allows multiple die stacks to be heated and bonded simultaneously without thermal crosstalk, maintaining high productivity while preventing premature curing in stacks that are not yet ready for bonding.
Solution Approach 2:
The substrate is modified to have different thermal properties in different regions - areas with channels have reduced thermal conductivity to isolate heat, while areas without channels maintain normal thermal properties for effective heat transfer to the bonding interface. This local differentiation enables selective heating of specific die stacks.
3Temperature
If channels are created in the substrate to reduce heat transfer, then heat isolation is improved, but substrate structural integrity may be compromised
Solution Approach 1:
The channels are designed as thin, strategic features etched into the substrate rather than large voids. These thin film-like separations provide sufficient thermal isolation while maintaining the overall structural integrity of the substrate. The channels are positioned and sized to minimize mechanical weakness while maximizing thermal isolation effectiveness.
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 significantly reduces unwanted heating of neighboring die stacks, improving yield, reliability, and throughput by ensuring proper interconnect formation in subsequent bonding processes.
Implementation Method 1
Modifying the substrate by creating channels that reduce or prevent heat transfer between die stacks
Data Source
AI summary
Methods for reducing heat transfer in semiconductor devices, and associated systems and devices, are described herein. In some embodiments, a method of manufacturing a semiconductor device includes forming a channel in a region of a substrate between a first die stack and a second die stack. The first die stack includes a plurality of first dies attached to each other by first film layers and the second die stack includes a plurality of second dies attached to each other by second film layers. The channel extends entirely through a thickness of the substrate. The method also includes applying heat to the first die stack to cure the first film layers. The channel reduces heat transfer from the first die stack to the second die stack.