Semiconductor Lid Non-Uniform Layering for TIM Strain Reduction
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Solution Overview
Problem
Thermal interface material (TIM) degradation occurs due to excessive mechanical strains caused by temperature excursions in semiconductor devices, leading to warpage and adhesive failure between the semiconductor die, lid, and substrate interfaces.
Innovation Solution
A semiconductor device design featuring a lid member with non-uniform layering having a different coefficient of thermal expansion (CTE) than the lid material, which induces warpage to offset the warpage of the substrate and semiconductor die, thereby reducing strains in the TIM interface during extreme temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a lid member is attached to the semiconductor die and substrate, then heat dissipation is improved, but thermal interface material degradation occurs due to excessive mechanical strains from temperature excursions
Solution Approach 1:
The patent applies thermal expansion principles by incorporating a compliance layer with a coefficient of thermal expansion (CTE) matched to the semiconductor die. This compliance layer expands and contracts with temperature changes in a manner that accommodates the die's thermal expansion, thereby reducing mechanical strain on the TIM during temperature excursions while maintaining effective heat dissipation through the lid member.
Solution Approach 2:
The patent uses composite materials by creating a multi-layer structure consisting of the lid member, compliance layer, and semiconductor die. The compliance layer acts as an intermediate composite material that bridges the thermal expansion mismatch between the rigid lid and the die, reducing stress concentration and preventing TIM degradation while preserving thermal conduction pathways.
2Strength
If the lid member is rigid to ensure structural stability, then mechanical strength is improved, but warpage occurs due to differences in thermal expansion coefficient between lid, die, and substrate
Solution Approach 1:
The patent addresses warpage by introducing a compliance layer with a specific CTE that is matched to the semiconductor die. This layer compensates for differential thermal expansion between the rigid lid and the die-substrate assembly, allowing the structure to maintain structural stability while accommodating thermal dimensional changes without excessive warpage.
Solution Approach 2:
The patent changes the physical parameters of the lid assembly by inserting a compliance layer with specific mechanical and thermal properties. This compliance layer has lower modulus and matched CTE compared to the rigid lid, fundamentally altering the thermal-mechanical response of the assembly to reduce warpage while maintaining overall structural integrity.
3Reliability
If temperature excursions are severe to test moisture resistance, then reliability testing is improved, but adhesive failure occurs between semiconductor die and TIM interface
Solution Approach 1:
The patent applies beforehand cushioning by pre-installing a compliance layer between the rigid lid and the semiconductor die. This compliance layer is specifically designed to cushion and absorb the mechanical stresses that occur during severe temperature excursions in moisture resistance testing, preventing adhesive failure at the TIM interfaces before such failures can occur during reliability testing.
Solution Approach 2:
The compliance layer's matched CTE to the semiconductor die allows it to expand and contract synchronously with the die during temperature excursions. This synchronous thermal expansion prevents differential stress accumulation at the adhesive interfaces, thereby preventing adhesive failure between the semiconductor die and TIM interface during rigorous moisture resistance testing.
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
The non-uniform layering on the lid member effectively opposes and offsets warpage, preventing large strains in the TIM interface and reducing adhesive failure, thus enhancing the reliability of semiconductor devices under temperature excursions.
Implementation Method 1
A layering is formed on portions of a top surface of the lid member. The layering will have a different coefficient of thermal expansion (CTE) than the lid member
Data Source
AI summary
A semiconductor device has a substrate having a top and bottom surface and a plurality of metal layers. A first die is electrically coupled to the top surface of the substrate. A lid member is attached to a top surface of the die and to the top surface of the substrate. A layering is formed on portions of a top surface of the lid member. The layering will have a different coefficient of thermal expansion (CTE) than the lid member.