Low-CTE Bonding Stage for Precise Chip Gap Control
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Solution Overview
Problem
In panel-level thermocompression bonding for semiconductor fabrication, there is a challenge in accurately controlling chip gap height due to thermal expansion and warpage issues caused by bond stages with high coefficients of thermal expansion, which affects the accuracy of chip alignment and process yield, especially in fine-pitch applications.
Innovation Solution
A thermocompression bonding tool using a bonding stage made of ultra-low coefficient of thermal expansion (CTE) ceramic materials, such as silicon and magnesium or indium, to minimize thermal expansion and warpage, enabling precise chip gap height control and maximizing process window for fine-pitch applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a bond stage with high coefficient of thermal expansion (CTE) is used, then the bonding process can be performed with conventional materials, but large variations in local expansion and warpage occur which adversely impact chip gap height control accuracy
Solution Approach 1:
The patent changes the material parameter (CTE) of the bond stage from high to ultra-low CTE ceramic materials. This parameter change directly reduces thermal expansion variations during heating cycles, minimizing warpage and improving chip gap height control accuracy to within ±1 micron.
Solution Approach 2:
The patent employs ultra-low CTE ceramic materials (such as silicon and magnesium or indium) for the bond stage, representing a transition to composite or specialized materials with superior thermal stability properties compared to conventional materials.
2Productivity
If panel size is increased to improve area utilization ratio and production cost, then manufacturing efficiency improves, but physical constraints such as panel warpage and handling capability deteriorate making processing operations difficult to control
Solution Approach 1:
The patent addresses panel warpage issues by using ultra-low CTE materials for the bond stage, which compensates for thermal expansion differences in large panels during heating, maintaining processing control stability despite increased panel size for improved productivity.
3Manufacturing precision
If force-based control process is used instead of position-based control, then some issues are addressed, but limitations remain especially for fine pitch applications requiring precise chip gap height control
Solution Approach 1:
The patent changes the fundamental control parameter from force-based to position-based control with direct measurement of chip gap height. This enables precise control of chip gap height within ±1 micron, making the process adaptable to fine pitch applications where such precision is critical.
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 ultra-low CTE ceramic materials reduces local expansion by approximately 90%, achieving <1 μm accuracy in chip gap height control and significantly increasing the process window for fine-pitch applications, thereby improving yield and performance.
Implementation Method 1
a bond head configured to heat and compress a semiconductor package assembly
Implementation Method 2
a bond head configured to heat and compress a semiconductor package assembly
Implementation Method 3
a bonding stage including a ceramic material including silicon and either magnesium or indium... reduces local expansion by approximately 90%
Data Source
AI summary
The present disclosure is directed to an apparatus having a bond head configured to heat and compress a semiconductor package assembly, and a bonding stage configured to hold the semiconductor package assembly, wherein the bonding stage comprises a ceramic material including silicon and either magnesium or indium.