Monolithic Silicon Die Stack for Thermal Dissipation Reliability
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Solution Overview
Problem
Conventional semiconductor device assemblies face challenges in thermal management due to the mismatch in thermal expansion coefficients between high thermal conductivity metals and semiconductor devices, leading to potential delamination, cracking, or mechanical damage during thermal cycling.
Innovation Solution
The use of a monolithic silicon structure with cavities for thermal dissipation, which is pre-populated with semiconductor devices and bonded to a lower die in a multi-die structure, providing improved thermal conductivity and matching thermal expansion characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high thermal conductivity metals are used for thermal dissipation, then thermal management performance is improved, but the mismatch in thermal expansion coefficients causes delamination, cracking, or mechanical damage
Solution Approach 1:
The patent introduces an intermediary material layer between the high thermal conductivity metal and the semiconductor die. This intermediary layer has thermal expansion properties that match the semiconductor die, serving as a buffer that absorbs expansion mismatch stresses during thermal cycling, thereby preventing delamination and cracking while allowing the metal layer to provide effective heat dissipation
Solution Approach 2:
The patent employs a composite structure consisting of multiple layers with different material properties. The composite includes a high thermal conductivity metal layer for heat dissipation, a semiconductor die, and an intermediary buffer layer. This composite material approach allows the system to simultaneously achieve high thermal management performance and mechanical reliability by combining materials with complementary properties
2Reliability
If conventional packaging processes are used to protect dies from environmental factors, then device protection is improved, but thermal dissipation capability deteriorates
Solution Approach 1:
The patent segments the packaging structure into distinct functional layers: a protective encapsulation layer for environmental protection, an intermediary buffer layer for thermal expansion management, and a high thermal conductivity metal layer for heat dissipation. This segmentation allows each layer to independently perform its specific function without compromising the others, enabling simultaneous achievement of device protection and thermal management
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 solution enhances thermal management in semiconductor device assemblies by reducing the risk of mechanical damage and maintaining thermal performance, while also allowing for the integration of additional semiconductor devices within the monolithic silicon structure.
Implementation Method 1
The use of a monolithic silicon structure with cavities for thermal dissipation, which is pre-populated with semiconductor devices and bonded to a lower die in a multi-die structure, providing improved thermal conductivity and matching thermal expansion characteristics
Implementation Method 2
The mismatch in thermal expansion coefficients between high thermal conductivity metals and semiconductor devices, leading to potential delamination, cracking, or mechanical damage during thermal cycling
Data Source
AI summary
A semiconductor device assembly is provided. The assembly includes a first semiconductor device including a plurality of electrical contacts on an upper surface thereof; a monolithic silicon structure having a lower surface in contact with the upper surface of the first semiconductor device, the monolithic silicon structure including a cavity extending from the lower surface completely through a body of the monolithic silicon structure to a top surface of the monolithic silicon structure; and a second semiconductor device disposed in the cavity, the second semiconductor device including a plurality of interconnects, each operatively coupled to a corresponding one of the plurality of electrical contacts.