Semiconductor Wafer Bonding via Metal Recrystallization
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Solution Overview
Problem
The existing methods for bonding semiconductor layers to conductive support substrates in LED production, such as eutectic bonding, require high temperatures, lead to complex layer structures, increased costs, and difficulties in preventing diffusion and void formation, especially for large-diameter wafers, resulting in reduced productivity and reliability.
Innovation Solution
A method involving the formation of metal layers with pyramid-shaped protrusions on both the semiconductor wafer and the support substrate, which are bonded at low temperatures through heating and compression, allowing for recrystallization and the formation of a strong junction layer without the need for barrier metals, thereby reducing voids and preventing warping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If eutectic bonding is used to bond semiconductor layer and conductive support substrate, then bonding strength is improved, but barrier metal layers are required which increases device complexity and production cost
Solution Approach 1:
The invention extracts and eliminates the barrier metal layers from the bonding structure by using a bonding method (fusion bonding or metal diffusion bonding) that does not require them, thereby simplifying the layer structure while maintaining bonding strength
Solution Approach 2:
The invention changes the bonding parameters from high-temperature eutectic bonding to low-temperature fusion bonding or metal diffusion bonding, which allows bonding without barrier metal layers and reduces the risk of material diffusion
2Reliability
If eutectic bonding is used, then bonding is achieved, but Sn or In diffusion occurs which corrodes metal layers and reduces reliability
Solution Approach 1:
The invention changes the bonding temperature parameter from high temperature (280-350°C for eutectic bonding) to low temperature (room temperature for fusion bonding or relatively low temperature for metal diffusion bonding), which prevents the diffusion and corrosion caused by Sn or In
Solution Approach 2:
The invention replaces the chemical bonding mechanism of eutectic bonding with physical bonding mechanisms (fusion bonding or metal diffusion bonding) that do not involve reactive eutectic materials, thereby eliminating the harmful diffusion and corrosion effects
3Strength
If eutectic bonding is used at high temperature, then bonding is achieved, but temperature unevenness causes void formation and wafer warping or destruction
Solution Approach 1:
The invention changes the temperature parameter from high temperature to low temperature bonding, which eliminates thermal expansion differences and prevents wafer warping, separation, or destruction while achieving uniform bonding without large voids
Solution Approach 2:
The invention converts the harmful effect of thermal expansion coefficient differences into a benefit by using low-temperature bonding, where thermal expansion is minimal, thereby preventing wafer warping and destruction
4Productivity
If eutectic bonding is used for large-diameter wafers, then bonding is attempted, but high temperature processing causes warping, separation, or destruction due to thermal expansion differences
Solution Approach 1:
The invention changes the temperature parameter to low temperature bonding, which eliminates the thermal expansion problems that make large-diameter wafer processing difficult, thereby enabling uniform bonding across large areas without warping or destruction
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 enables uniform bonding of large-diameter semiconductor wafers to support substrates at low temperatures, minimizing voids and warping, and enhancing the productivity and reliability of LED elements by eliminating the need for barrier metals and high-temperature processing.
Implementation Method 1
a first treatment step of heating and compressing together the first metal layer and the second metal layer placed opposite to each other, thereby bonding them with maintaining a junction interface between the first metal layer and the second metal layer
Implementation Method 2
a second treatment step of heating the first metal layer and the second metal layer to make the junction interface disappear
Data Source
AI summary
A manufacturing method of a semiconductor element which can improve productivity and reliability, comprises a step of forming a device structure layer including a semiconductor layer on a first substrate; a step of forming a first metal layer on the device structure layer; a step of forming a second metal layer made of the same material as the first metal layer on a second substrate; a first treatment step of heating and compressing together the first metal layer and the second metal layer placed opposite to each other, thereby bonding them with maintaining a junction interface between the first and second metal layers; and a second treatment step of heating the first and second metal layers to make the junction interface disappear. Either one of the first and second metal layers has a coarse surface having multiple pyramid-shaped protrusions formed at its surface.