Thermocompression Bonding Control for Panel Warpage and Chip Alignment
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Solution Overview
Problem
In panel-level packaging for semiconductor fabrication, physical constraints such as panel warpage and handling limitations of processing tools hinder the use of larger panels, leading to difficulties in controlling thermocompression bonding processes and resulting in low yields.
Innovation Solution
A thermocompression bonding tool with a bond head, stage, camera, and controller is developed, incorporating a recipe displacement and temperature profile, along with offsets for chip gap height and alignment control, to address thermal expansion and mechanical stiffness variations, ensuring accurate placement and bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If larger panels are used in panel-level packaging, then area utilization ratio and production cost efficiency are improved, but panel warpage and handling capability deteriorate
Solution Approach 1:
The patent applies parameter changes by implementing dynamic control of thermal parameters (temperature profiles, heating rates) and mechanical parameters (pressure distribution, bonding force) during thermocompression bonding. This allows the process to accommodate panel warpage and maintain bonding quality on large panels by adjusting parameters in real-time based on panel characteristics and thermal expansion behavior.
2Area of stationary object
If larger panels are used in panel-level packaging, then area utilization ratio and production cost efficiency are improved, but handling capability of processing tools deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the large panel into multiple bond locations that are processed sequentially rather than attempting to handle the entire large panel at once. The system uses automated tooling that can position and bond chips at different locations across the panel, breaking down the complex handling task into manageable segments.
3Productivity
If thermocompression bonding is performed on large panels, then panel-level packaging productivity is improved, but manufacturing precision deteriorates due to thermal expansion and mechanical stiffness variations
Solution Approach 1:
The patent applies feedback by implementing a control system that uses measured offsets from pre-production bonding tests to adjust and correct bonding parameters during production. The system continuously monitors and compensates for thermal expansion and mechanical stiffness variations by applying correction factors based on actual measurements, maintaining precision despite variations in panel properties.
Solution Approach 2:
The patent applies preliminary action by performing pre-production bonding tests to characterize panel-specific thermal expansion and mechanical properties before actual production bonding. These preliminary tests establish offset values and process parameters that are then used to guide the production bonding process, ensuring precision is achieved before high-volume manufacturing begins.
4Extent of automation
If automated thermocompression bonding is implemented, then labor cost and consistency are improved, but process control complexity increases due to multiple input parameters
Solution Approach 1:
The patent applies parameter changes by systematically varying and optimizing multiple process parameters including temperature profiles, bonding pressure, heating rates, and hold times. The automated system controls these parameters through programmed sequences that adapt to specific panel and chip requirements, managing complexity through structured parameter management rather than simplifying the parameters themselves.
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 solution provides high accuracy in x, y, z, and theta placements, thermal expansion compensation, and mechanical compensation, enhancing yield and performance in panel-level manufacturing by maintaining precise chip gap heights and alignments.
Implementation Method 1
thermal expansion compensation
Implementation Method 2
applying thermal and mechanical pressure
Data Source
AI summary
The present disclosure is directed to a thermocompression bonding tool having a bond head with a surface for compression and heating and a sensor, a stage for compression and heating, and a controller, and a method for its use for chip gap height and alignment control. For chip gap height and alignment control, the controller is provided with a recipe displacement and temperature profile and measured offsets.