Hybrid Diffusion Barrier Structure for Wafer-Bonded Semiconductor Pads
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Solution Overview
Problem
Existing semiconductor packages face challenges in preventing metal diffusion from conductive pads into adjacent dielectric layers during wafer bonding, leading to increased leakage current and reduced reliability.
Innovation Solution
Incorporating a hybrid diffusion barrier system with organic and inorganic materials around conductive pads, where the organic layer covers the lateral surface and an inorganic layer covers the bottom surface, to inhibit copper diffusion, ensuring effective adhesion and reducing misalignment issues during wafer bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-material diffusion barrier is used around conductive pads, then the structure is simple and manufacturing is easier, but copper diffusion cannot be effectively prevented during wafer bonding
Solution Approach 1:
The patent applies composite materials by combining organic and inorganic diffusion barrier materials to form a hybrid barrier system. The organic layer (e.g., polyimide or benzocyclobutene) provides initial diffusion prevention, while the inorganic layer (e.g., silicon oxide or silicon nitride) provides enhanced barrier properties. This composite structure effectively prevents copper diffusion during wafer bonding that cannot be achieved with single-material barriers alone.
Solution Approach 2:
The diffusion barrier is segmented into multiple functional layers: an organic diffusion barrier layer applied first, followed by an inorganic diffusion barrier layer applied second. This segmentation allows each layer to perform its specific function optimally - the organic layer provides flexibility and initial protection, while the inorganic layer provides robust thermal and chemical barrier properties during the bonding process.
2Manufacturing precision
If wafer bonding is performed without adequate diffusion barriers, then the bonding process is simpler and faster, but misalignment occurs between conductive pads leading to increased leakage current
Solution Approach 1:
The patent applies preliminary action by forming the hybrid diffusion barrier system (organic layer followed by inorganic layer) before performing the wafer bonding process. This pre-formed barrier structure provides precise alignment references and protects against misalignment during bonding, preventing copper pad-to-dielectric short circuits that would increase leakage current.
Solution Approach 2:
The hybrid diffusion barrier acts as an intermediary layer between the conductive copper pads and the surrounding dielectric material. During wafer bonding, this intermediate barrier structure prevents direct contact between copper and dielectric even when misalignment occurs, thereby maintaining manufacturing precision without requiring extremely tight bonding tolerances.
3Reliability
If copper diffusion is not prevented, then the device structure remains simpler, but leakage current increases and reliability decreases
Solution Approach 1:
The patent uses composite materials combining organic diffusion barrier (such as polyimide or benzocyclobutene) and inorganic diffusion barrier (such as silicon oxide or silicon nitride) layers. This composite structure provides superior copper diffusion prevention compared to single-material barriers, effectively reducing leakage current by blocking copper atom migration into the dielectric layer during and after wafer bonding.
Solution Approach 2:
The patent applies parameter changes by selecting materials with specific properties - the organic layer provides flexibility and adhesion, while the inorganic layer provides thermal stability and superior diffusion blocking. The thickness and material composition of each layer are optimized to achieve the required diffusion prevention performance, thereby reducing leakage current while managing the complexity of the barrier system.
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 hybrid diffusion barrier system effectively prevents copper diffusion, enhancing the semiconductor device's reliability by reducing leakage current and improving adhesion between semiconductor chips.
Implementation Method 1
a first diffusion barrier in contact with a bottom surface of the first conductive pad; and a second diffusion barrier in contact with a lateral surface of the first conductive pad
Implementation Method 2
a first silicon oxide layer on the first organic layer and spaced apart in a first direction from the lateral surface of the first conductive pad across the first organic layer
Implementation Method 3
A diffusion rate of copper in the conductive layer and a diffusion rate of copper in the first dielectric layer may be less than a diffusion rate of copper in the second dielectric layer
Data Source
AI summary
A semiconductor device includes a first semiconductor chip that includes a first conductive pad whose top surface is exposed; and a second semiconductor chip that includes a second conductive pad whose top surface is exposed and in contact with at least a portion of the top surface of the first conductive pad. The first semiconductor chip may include a first diffusion barrier in contact with a bottom surface of the first conductive pad, and a second diffusion barrier in contact with a lateral surface of the first conductive pad, and the first diffusion barrier and the second diffusion barrier may include different materials from each other.