Semiconductor Package Trench Cavity for Electroless Plating Bridging
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Solution Overview
Problem
Conventional electroless Cu-to-Cu bonding experiences issues with non-stationary spacers affecting the flow of electroless plating solution and increased lateral bridging due to high I/O density, which complicates low-temperature bonding operations.
Innovation Solution
A semiconductor package design featuring a first and second substrate with recessed trenches forming a pathway cavity, including metal and insulating protrusions that are staggeredly disposed to create a defined and stationary pathway for electroless plating, preventing bridging between conductive elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-stationary spacers are used between opposing bonding surfaces, then a pathway for electroless plating solution is created, but the flow of electroless plating solution is affected and lateral bridging frequently occurs
Solution Approach 1:
The bonding interface is segmented into multiple discrete regions by forming isolated protrusions (both conductive and insulating) on the bonding surfaces. These protrusions divide the bonding area into multiple pathway cavities, allowing controlled fluid flow through defined channels while preventing uncontrolled lateral bridging between adjacent bonding regions.
Solution Approach 2:
Insulating protrusions are introduced as intermediary elements between conductive protrusions on opposing bonding surfaces. These insulating structures act as mediators that guide the electroless plating solution flow and prevent direct lateral bridging between adjacent conductive elements, ensuring controlled metal deposition only at intended bonding locations.
2Productivity
If I/O density is increased, then bonding capacity is improved, but lateral bridging frequently occurs
Solution Approach 1:
The bonding surface is designed with locally differentiated properties where insulating protrusions are strategically positioned between conductive protrusions. This local quality differentiation creates distinct zones: conductive regions for metal deposition and insulating regions for fluid guidance and bridging prevention, enabling high I/O density while maintaining precise control over lateral bridging.
Solution Approach 2:
The bonding structure employs asymmetric arrangement of protrusions with different heights and materials. Conductive protrusions extend to different heights than insulating protrusions, creating an asymmetric profile that guides fluid flow directionally and prevents lateral bridging even at high I/O densities where symmetric arrangements would fail.
3Temperature
If low temperature bonding operation is used, then chip performance is preserved, but bonding process complexity increases
Solution Approach 1:
The protrusions (both conductive and insulating) are pre-formed on the bonding surfaces before the low-temperature electroless plating process. This preliminary structuring of the bonding interface with defined pathway cavities eliminates the need for complex real-time process control during bonding, simplifying the overall low-temperature bonding process while maintaining chip performance.
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 design enhances the flow dynamics of electroless plating solutions and prevents lateral bridging, ensuring reliable and efficient metal-to-metal bonding even at high I/O counts, thereby maintaining chip performance during low-temperature bonding operations.
Implementation Method 1
bonding the first substrate and the second substrate by an electroless plating operation
Data Source
AI summary
Present disclosure provides a semiconductor package, including a first substrate having a first active surface and a first trench recessed from the first active surface, a second substrate having a second trench facing the first trench, and a pathway cavity defined by the first trench and the second trench. The first trench comprises a first metal protrusion and a first insulating protrusion. A method for manufacturing the semiconductor package described herein is also disclosed.