Semiconductor Chip Soldering with Indium-Tin and Gold Layers
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Solution Overview
Problem
The difference in thermal expansion behavior between semiconductor chips and substrates during the soldering process leads to mechanical stresses, causing cracks or failure in solder joints when electronic components are subjected to mechanical loads.
Innovation Solution
A method involving a solder metal layer sequence with an indium-tin alloy and a gold layer, separated by a barrier layer, is applied between the semiconductor chip and substrate, forming intermetallic layers that reduce thermal expansion stresses and enhance mechanical resilience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If gold-tin solder is used for soldering semiconductor chips onto a substrate at high temperature (300°C), then strong bonding is achieved, but considerable thermally induced mechanical loads occur during cooling due to different thermal expansion behavior, leading to solder joint failure or crack initiation
Solution Approach 1:
The solder joint is segmented into multiple layers with different materials (first metallic layer, barrier layer, second metallic layer) to distribute and manage thermal stresses. Each layer serves a specific function: the first metallic layer provides bonding, the barrier layer prevents interdiffusion, and the second metallic layer enhances ductility and reduces brittleness, collectively improving reliability while maintaining strength.
Solution Approach 2:
A composite solder structure is created using multiple materials with complementary properties. The combination of metallic layers (providing strength and bonding) and barrier layers (providing diffusion protection and stress management) creates a composite joint that simultaneously achieves high bonding strength and improved reliability under thermal cycling conditions.
2Ease of manufacture
If a simple solder layer is used to connect semiconductor chip to substrate, then manufacturing is simple, but the connection is brittle and prone to failure under mechanical load
Solution Approach 1:
The solder connection is divided into multiple functional layers that can be applied through standardized deposition processes. This segmentation allows each layer to be optimized for its specific function while maintaining overall manufacturing efficiency through established multi-layer deposition techniques.
Solution Approach 2:
A composite layer structure is implemented combining metallic layers for bonding and barrier layers for protection. This composite approach enhances mechanical resilience and reduces brittleness while remaining compatible with existing manufacturing processes for applying multiple thin layers.
3Reliability
If high soldering temperature (300°C) is used to achieve strong bonding, then reliable solder joint formation occurs, but high thermally induced mechanical loads occur during cooling due to thermal expansion differences
Solution Approach 1:
The thermal stress management is achieved through segmentation of the joint into multiple layers with different thermal and mechanical properties. This allows the first metallic layer to provide strong bonding at soldering temperature while the second metallic layer and barrier layers manage the thermal expansion differences during cooling, reducing overall mechanical loads.
Solution Approach 2:
A composite layer structure is used where different materials are combined to simultaneously achieve reliable solder joint formation at high temperature and reduce thermally induced mechanical loads during cooling. The composite structure allows each material to contribute its optimal properties for different stages of the thermal cycle.
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 method creates a robust, ductile, and less brittle intermetallic layer, ensuring a solid and permanent connection of the semiconductor chip to the substrate, reducing the risk of detachment or cracking under mechanical loads and maintaining a stable connection.
Implementation Method 1
Heating the arrangement produced under E) for fastening the semiconductor chip on the substrate. In particular, in step F) the metallization layer sequence and the solder metal layer sequence form a bonding layer sequence.
Implementation Method 2
a solder metal layer sequence comprising a first metallic layer, a barrier layer arranged above the first metallic layer, and a second metallic layer arranged between the barrier layer and the semiconductor chip
Data Source
AI summary
A method for fastening a semiconductor chip on a substrate and an electronic component are disclosed. In an embodiment a method includes providing a semiconductor chip, applying a solder metal layer sequence on the semiconductor chip, providing a substrate, applying a metallization layer sequence on the substrate, applying the semiconductor chip on the substrate via the solder metal layer sequence and the metallization layer sequence and heating the applied semiconductor chip on the substrate for fastening the semiconductor chip on the substrate. The solder metal layer may include a first metallic layer comprising an indium-tin alloy, a barrier layer arranged above the first metallic layer and a second metallic layer comprising gold arranged between the barrier layer and the semiconductor chip, wherein an amount of substance of the gold in the second metallic layer is greater than an amount of substance of tin in the first metallic layer.