Copper I/O Pad Structure With Passivation-Controlled Etching
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Solution Overview
Problem
Existing IC manufacturing processes face challenges in forming planar and reliable I/O pads due to the use of aluminum-based layers, which are soft and prone to damage during etching, leading to increased resistance and difficulty in scaling down geometry size.
Innovation Solution
The use of copper-based metal layers formed through electro-chemical plating (ECP) with a subsequent passivation structure configuration and controlled etching processes to create planar and reliable I/O pads, which reduces parasitic resistance and enhances the reliability and/or performance of the semiconductor structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aluminum-based layers are used for I/O pads, then the manufacturing process is simple, but the pads are soft and prone to damage during etching, leading to increased resistance
Solution Approach 1:
The patent changes the material parameter from aluminum-based layers to copper-based metal layers formed through electro-chemical plating (ECP). This material substitution fundamentally alters the physical properties of the I/O pads, providing superior mechanical strength and etching resistance while maintaining manufacturing feasibility through the ECP process
Solution Approach 2:
The patent employs a composite structure consisting of multiple layers: copper-based metal layers formed by ECP, barrier layers, and passivation structures. This multi-layer composite approach combines the advantages of each material to achieve both high reliability (through copper's strength and conductivity) and ease of manufacture (through standardized deposition and plating processes)
2Ease of manufacture
If aluminum-based layers are used for I/O pads, then the process is easier to manufacture, but the pads are prone to damage leading to increased resistance
Solution Approach 1:
The patent changes the material parameter from aluminum-based layers to copper-based metal layers formed through electro-chemical plating (ECP). This material substitution fundamentally alters the physical properties of the I/O pads, providing superior mechanical strength and etching resistance while maintaining manufacturing feasibility through the ECP process
Solution Approach 2:
The patent applies beforehand cushioning by forming a passivation structure over the copper-based metal layers before subsequent processing steps. This protective layer is deposited in advance to prevent damage to the I/O pads during etching and other manufacturing processes, ensuring pad integrity without complicating the overall manufacturing flow
3Device complexity
If conventional etching processes are used, then the process flow is simple, but the conductive features in RDL are damaged
Solution Approach 1:
The patent applies beforehand cushioning by forming a passivation structure over the copper-based metal layers before subsequent processing steps. This protective layer is deposited in advance to prevent damage to the I/O pads during etching and other manufacturing processes, ensuring pad integrity without complicating the overall manufacturing flow
Solution Approach 2:
The passivation structure serves as an intermediary protective layer between the copper-based conductive features and the etching process. This mediator layer allows the etching process to proceed while protecting the underlying conductive features from damage, effectively decoupling the simplicity of the etching process from the need for feature protection
4Ease of manufacture
If I/O pads are formed with aluminum-based layers, then the initial formation is easier, but scaling down geometry size becomes difficult
Solution Approach 1:
The patent changes the material parameter from aluminum-based layers to copper-based metal layers formed through electro-chemical plating (ECP). This material substitution fundamentally alters the physical properties of the I/O pads, providing superior mechanical strength and etching resistance while maintaining manufacturing feasibility through the ECP process
Solution Approach 2:
The patent replaces the conventional mechanical deposition and patterning approach with electro-chemical plating (ECP) for forming copper-based metal layers. This substitution enables better control over layer formation and geometry, facilitating scaling down while maintaining manufacturing ease through the self-organizing nature of electrochemical deposition
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 use of copper-based metal plating (ECP) with a subsequent passivation structure and a controlled etching process to form a planar and reliable I/O pads, which reduces parasitic resistance and enhances the reliability and enhances the effectiveness of the semiconductor structure.
Implementation Method 1
forming a copper layer over the substrate and in the via opening, upon completion of the electro-chemical plating process
Data Source
AI summary
Semiconductor structures and methods are provided. An exemplary method includes receiving a structure comprising a metal feature, a first passivation structure over the metal feature, and a first opening extending through the first passivation structure and exposing the metal feature. The exemplary method also includes forming a conductive layer in the first opening; forming a second passivation structure over the conductive layer, performing a first etching process to form a second opening extending through the second passivation structure and exposing the conductive layer, performing a second etching process to selectively remove an upper portion of the second passivation structure to enlarge an upper portion of the second opening, and after the performing of the second etching process, forming a conductive feature in the second opening.