Metal Pad Passivation Structure for Moisture and Hydrogen Isolation
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Solution Overview
Problem
Existing integrated circuit technologies face challenges in effectively isolating metal pads from detrimental substances like hydrogen and moisture, which can damage sensitive components such as memory cells and low-k dielectric layers, leading to reliability issues.
Innovation Solution
A dual-layer isolation structure is formed around metal pads, comprising a penetration-resistant isolation layer and a protection layer, with the less-dense dielectric layers being laterally recessed to enhance isolation, using a combination of anisotropic and isotropic etching processes to create a self-adjusting barrier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a standard passivation layer is formed over metal pads, then the metal pads are protected to some extent, but harmful substances like hydrogen and moisture can still penetrate through to damage sensitive components
Solution Approach 1:
The passivation structure is divided into multiple functional layers: a first passivation layer (e.g., silicon oxide) and a second passivation layer (e.g., silicon nitride) with different material properties. This segmentation allows each layer to provide specific protection functions, with the second layer offering superior barrier properties against hydrogen and moisture penetration, thereby resolving the contradiction between basic protection and enhanced reliability.
Solution Approach 2:
The patent employs composite passivation structures combining different dielectric materials (such as silicon oxide and silicon nitride layers) with complementary properties. The composite structure leverages the low-k properties of silicon oxide for stress management and the high barrier properties of silicon nitride for moisture and hydrogen isolation, achieving both protection and harm prevention simultaneously.
2Stability of the object's composition
If dielectric layers are deposited conformally over metal pads, then complete coverage is achieved, but harmful substances can still penetrate through less-dense dielectric regions
Solution Approach 1:
The patent implements local quality enhancement by laterally recessing less-dense dielectric layers (such as low-k oxide layers) relative to denser dielectric layers or isolation structures. This creates overlapping regions where the denser, more penetration-resistant materials provide enhanced barrier protection at critical interfaces and edges, preventing harmful substance penetration through vulnerable less-dense regions while maintaining overall coverage.
3Reliability
If lateral recessing of less-dense dielectric layers is performed, then penetration resistance is enhanced, but the manufacturing process becomes more complex
Solution Approach 1:
The patent applies preliminary action by forming the lateral recesses of less-dense dielectric layers during the same etching process used to create contact holes or vias. The etch masks and process parameters are designed in advance to simultaneously achieve both the contact openings and the lateral recessing, eliminating the need for separate recessing steps and reducing overall manufacturing complexity while maintaining enhanced penetration resistance.
Solution Approach 2:
The etching process is designed to serve multiple functions: creating contact holes, forming lateral recesses of less-dense dielectric layers, and defining isolation structures. This multi-functional approach consolidates several manufacturing operations into a single process step, reducing device complexity while achieving the desired penetration resistance through lateral recessing.
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 dual-layer isolation structure significantly reduces the penetration of harmful substances, enhancing the reliability and integrity of integrated circuit components by providing improved moisture and hydrogen isolation.
Implementation Method 1
performing a first anisotropic etching process to etch through the second dielectric layer and the first dielectric layer
Implementation Method 2
performing an isotropic etching process to laterally etch the first dielectric layer and the second dielectric layer
Data Source
AI summary
A method includes depositing a first dielectric layer covering an electrical connector, depositing a second dielectric layer over the first dielectric layer, and performing a first etching process to etch-through the second dielectric layer and the first dielectric layer. An opening is formed in the first dielectric layer and the second dielectric layer to reveal the electrical connector. A second etching process is performed to laterally etch the first dielectric layer and the second dielectric layer. An isolation layer is deposited to extend into the opening. The isolation layer has a vertical portion and a first horizontal portion in the opening, and a second horizontal portion overlapping the second dielectric layer. An anisotropic etching process is performed on the isolation layer, with the vertical portion of the isolation layer being left in the opening.