Semiconductor Bump Structure With Controlled UBM Undercuts
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Solution Overview
Problem
The reduction in size of semiconductor device bumps increases the likelihood of failure due to undercuts in the under bump metallization (UBM) layer during etching, leading to potential collapse of the bumps.
Innovation Solution
A novel method is introduced to form bump structures that minimize undercuts in the UBM layer by controlling the etching process, ensuring partial or no undercut formation through strategic photoresist masking and selective etching of conductive connection patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the size of semiconductor device bumps is reduced to meet consumer demand for smaller devices, then the device size decreases and productivity improves, but the likelihood of bump failure due to undercuts in the UBM layer increases
Solution Approach 1:
The patent applies preliminary action by forming a mandrel structure with controlled geometry before depositing the UBM layer and bump materials. The mandrel's specific shape and dimensions are predetermined to control the etching process and prevent undercuts from forming, thereby proactively preventing the reliability issue before it occurs during subsequent processing steps.
Solution Approach 2:
The mandrel structure serves as an intermediary element that mediates between the bump formation process and the UBM layer. This intermediate structure controls the interface geometry and etching behavior, preventing direct harmful interaction between the etching process and the UBM layer that would cause undercuts and bump failure.
2Ease of manufacture
If conventional etching processes are used to form bump structures, then manufacturing simplicity is maintained, but undercuts form in the UBM layer causing bump collapse
Solution Approach 1:
The mandrel structure is formed in advance with predetermined geometry that controls the etching process outcomes. By preparing this structural framework beforehand, the patent achieves precise undercut control without requiring complex etching process adjustments, maintaining manufacturing simplicity while improving precision.
Solution Approach 2:
The patent changes the geometric parameters of the mandrel structure (shape, size, configuration) to control the etching process behavior. By adjusting these physical parameters of the intermediate structure, the patent achieves precise control over undercut formation without complicating the etching process itself.
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 approach reduces the risk of bump collapse by controlling the location and extent of undercuts, enabling high aspect ratio bumps with reduced defects and improved reliability in semiconductor devices.
Implementation Method 1
strategic photoresist masking
Implementation Method 2
selective etching of conductive connection patterns
Data Source
AI summary
In a method of manufacturing a semiconductor device first conductive layers are formed over a substrate. A first photoresist layer is formed over the first conductive layers. The first conductive layers are etched by using the first photoresist layer as an etching mask, to form an island pattern of the first conductive layers separated from a bus bar pattern of the first conductive layers by a ring shape groove. A connection pattern is formed to connect the island pattern and the bus bar pattern. A second photoresist layer is formed over the first conductive layers and the connection pattern. The second photoresist layer includes an opening over the island pattern. Second conductive layers are formed on the island pattern in the opening. The second photoresist layer is removed, and the connection pattern is removed, thereby forming a bump structure.