Protected Copper Die Attach Layer for Oxidation-Resistant Packaging
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Solution Overview
Problem
Copper layers on die attach surfaces of microelectronic devices face challenges due to contamination, oxidation, and corrosion, making integration into fabrication flows difficult.
Innovation Solution
A method involving thinning the substrate, forming a copper-containing layer with an intermediate layer to enhance adhesion and prevent diffusion, and applying a protective metal layer to prevent corrosion and oxidation, which can be optionally removed before assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper layers are integrated on die attach surfaces to provide low resistance electrical and thermal connections, then electrical and thermal conductivity is improved, but contamination, oxidation, and corrosion issues worsen
Solution Approach 1:
A nickel-containing protective layer is introduced as an intermediary between the copper-containing layer and the external environment. This protective layer acts as a barrier that prevents contamination, oxidation, and corrosion of the copper layer while allowing the copper to maintain its low resistance electrical and thermal connection properties.
Solution Approach 2:
The invention creates a composite structure consisting of multiple layers: a copper-containing layer for electrical and thermal conduction, and a nickel-containing protective layer for corrosion and oxidation resistance. This composite material approach combines the advantages of different materials to achieve both high conductivity and environmental stability.
2Reliability
If copper layers are integrated on die attach surfaces, then electrical and thermal conductivity is improved, but integration difficulty into fabrication flows worsens
Solution Approach 1:
The protective nickel-containing layer is formed over the copper-containing layer before subsequent fabrication steps. This preliminary protective action prevents contamination and oxidation that would otherwise occur during later processing steps, thereby simplifying the overall fabrication flow by eliminating the need for additional protective measures later in the process.
3Reliability
If a protective metal layer is formed on the copper-containing layer to prevent corrosion and oxidation, then reliability is improved, but process complexity increases
Solution Approach 1:
The formation of the protective nickel-containing layer is merged with the existing copper layer formation process. Both layers are deposited in sequence during the same fabrication stage, combining two protective functions into a single integrated process step rather than requiring separate, additional processing stages.
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 reduces copper contamination, maintains low thermal and electrical resistance, and ensures reliable attachment to package die mount areas with reduced process complexity and cost.
Implementation Method 1
copper's high electrical and thermal conductivities
Implementation Method 2
copper's high electrical and thermal conductivities
Implementation Method 3
protective metal layer to prevent corrosion and oxidation
Data Source
AI summary
A microelectronic device is formed by thinning a substrate of the microelectronic device from a die attach surface of the substrate, and forming a copper-containing layer on the die attach surface of the substrate. A protective metal layer is formed on the copper-containing layer. Subsequently, the copper-containing layer is attached to a package member having a package die mount area. The protective metal layer may optionally be removed prior to attaching the copper-containing layer to the package member. Alternatively, the protective metal layer may be left on the copper-containing layer when the copper-containing layer is attached to the package member. A structure formed by the method is also disclosed.