Bondhead Vacuum Layout for Thermocompression Vapor Control
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Solution Overview
Problem
Conventional thermocompression bonding processes face contamination issues due to vaporization of bonding materials, leading to clogs, reduced vacuum strength, and contamination of bondheads and semiconductor dies, which affects die stacking accuracy and interconnect quality, especially in high-temperature bonding of multiple semiconductor dies.
Innovation Solution
A supplemental vacuum source is applied around the bondhead to draw in and retain offgassing vapors, reducing contamination and improving die placement accuracy and interconnect reliability by creating a path for vaporized bonding material to be withdrawn before it reaches the bondhead, thereby extending equipment life and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high temperature bonding is used to ensure appropriate viscosity and reliable interconnects, then bonding reliability is improved, but bonding material vaporization increases causing contamination and vacuum line clogs
Solution Approach 1:
The harmful vaporized bonding material is extracted from the bonding zone by the vacuum system before it can contaminate the bondhead or enter vacuum lines. The vacuum source continuously removes offgassing during the bonding process, separating the harmful vapor from the bonding interface.
Solution Approach 2:
A film assist bonding (FAB) tape is introduced as an intermediary layer between the bonding material and the bondhead. This tape acts as a physical barrier that prevents vaporized bonding material from reaching and contaminating the bondhead surface, while still allowing thermal energy to pass through for bonding.
2Object-generated harmful factors
If film assist bonding tape is used to reduce contamination, then bondhead contamination is reduced, but device complexity and manufacturing cost increase
Solution Approach 1:
Instead of adding a FAB tape barrier, the solution extracts the harmful vapor at its source using a vacuum system. This removes the need for the additional FAB tape layer, simplifying the bonding process while still preventing contamination.
Solution Approach 2:
The mechanical barrier approach (FAB tape) is replaced with a pneumatic/vacuum approach. The vacuum system uses pressure differentials to remove vapors, substituting a field-based solution for a material-based barrier, thereby reducing complexity.
3Ease of manufacture
If conventional bonding process is used, then manufacturing simplicity is maintained, but vacuum strength decreases over time due to vapor condensation in vacuum lines
Solution Approach 1:
The vacuum system is activated before and during the bonding process to preemptively remove vapors as they are generated. This preliminary action prevents vapor condensation in the vacuum lines before it can occur, maintaining vacuum strength throughout the bonding operation.
Solution Approach 2:
The vacuum source operates continuously during the bonding process, providing ongoing removal of offgassing vapors. This continuous action ensures that vacuum strength is maintained throughout the entire bonding operation, preventing the gradual degradation seen in conventional processes.
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 supplemental vacuum system effectively inhibits vapor deposition on bondheads and adjacent components, enhancing die stack reliability, reducing defects, and allowing for higher process capability without the need for film assist bonding tape, thus improving manufacturing efficiency and reducing downtime.
Implementation Method 1
a vacuum source configured to draw a vacuum through the opening to retain the semiconductor die during bonding
Implementation Method 2
the bonding material can vaporize at the higher temperatures
Implementation Method 3
A supplemental vacuum source is applied around the bondhead to draw in and retain offgassing vapors
Implementation Method 4
the vapor can enter and condense within the vacuum lines of the bondhead, leading to clogs
Data Source
AI summary
Systems and methods for controlling contamination during thermocompression bonding are provided herein. The tool generally includes a bondhead having a first channel extending in a lateral direction from a first port along a second side toward a perimeter of the bondhead. In several examples, the bondhead includes a second channel fluidly coupled to a second port and extending in a lateral direction along an inset surface of the bondhead, where the second channel at least partially surrounds the first channel. In other examples, the tool includes a vacuum manifold having a vacuum opening positioned laterally outward from the bondhead. A first flow unit is coupled to the first channel and is configured to withdraw air. A second flow unit is coupled to the second port or the manifold to withdraw fluid and prevent outgassing bonding materials from entering the first channel, depositing on the bondhead, and/or contaminating neighboring semiconductor components.