UBM Layer Alignment for Semiconductor Die Stability
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Solution Overview
Problem
Semiconductor devices face challenges in aligning and securing semiconductor die during the encapsulation process, leading to potential shifting and reduced manufacturing yield due to the difficulty in maintaining precise alignment of interconnect structures.
Innovation Solution
A method involving the use of a temporary carrier with a fixed Under Bump Metallization (UBM) layer and conductive pillars to align and secure the semiconductor die, ensuring stability during encapsulation, and forming interconnect structures through these pillars for electrical connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional die attachment and encapsulation processes are used, then the encapsulation process can be completed, but the semiconductor die shift during mounting and encapsulation leading to misalignment with interconnect structures
Solution Approach 1:
The UBM layer is formed and fixed to the interconnect structure before die attachment. This preliminary formation of the UBM layer with alignment features provides a stable reference structure that enables precise die alignment during subsequent mounting operations, preventing die shift during encapsulation.
Solution Approach 2:
The UBM layer serves as an intermediary component between the interconnect structure and the semiconductor die. It provides a stable bonding interface with alignment features that facilitate precise die placement and maintain alignment stability throughout the encapsulation process.
2Reliability
If via formation and filling processes are used to create interconnect structures, then electrical connectivity can be achieved, but the semiconductor die are difficult to align during die attachment
Solution Approach 1:
The UBM layer with alignment features is formed on the interconnect structure before die attachment. This preliminary structure provides visual or physical alignment references that guide precise die placement, ensuring both electrical connectivity and alignment precision.
3Area of moving object
If smaller die size is achieved through front-end process improvements, then device footprint is reduced and performance is improved, but alignment difficulty increases during die attachment
Solution Approach 1:
The UBM layer acts as an intermediary that provides enlarged alignment features relative to the small die size. These alignment features on the UBM layer facilitate precise positioning of small-dimension dies, overcoming the increased alignment difficulty associated with reduced die area.
Solution Approach 2:
The UBM layer incorporates localized alignment features at specific positions where dies will be attached. These local alignment features provide precise positioning references without requiring the entire die or interconnect structure to be larger, maintaining small overall device footprint while enabling high alignment precision.
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 prevents die shifting during encapsulation, enhances manufacturing yield by ensuring precise alignment and electrical connectivity, and allows for the formation of stacked semiconductor devices with improved structural support and functionality.
Implementation Method 1
The UBM layer prevents shifting of the semiconductor die while depositing the encapsulant
Implementation Method 2
The first and second interconnect structures are electrically connected through the conductive pillar
Implementation Method 3
depositing an encapsulant over the semiconductor die and around the conductive pillar
Data Source
AI summary
A semiconductor device is made by forming a first conductive layer over a temporary carrier. A UBM layer is formed over the temporary carrier and fixed in position relative to the first conductive layer. A conductive pillar is formed over the first conductive layer. A semiconductor die is mounted to the UBM layer to align the die relative to the conductive pillar. An encapsulant is deposited over the die and around the conductive pillar. The UBM layer prevents shifting of the semiconductor die while depositing the encapsulant. The temporary carrier is removed. A first interconnect structure is formed over a first surface of the encapsulant. A second interconnect structure is formed over a second surface of the encapsulant. The first and second interconnect structures are electrically connected through the conductive pillar. The first or second interconnect structure includes an integrated passive device electrically connected to the conductive pillar.