Wafer Bonding Apparatus Thermal Isolation via Flexible Rods
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Solution Overview
Problem
Existing chip thermocompression-bonding tools face challenges in maintaining flatness and accuracy when bonding large-area wafers due to heat deformation and thermal expansion issues, leading to increased heating and cooling times and reduced operational efficiency.
Innovation Solution
A bonding device with a unique structure featuring rod-shaped flexible members and a heating member with a linear expansion coefficient matching the pressure plate units, which applies pressure and heat while minimizing heat transfer to the tool body, maintaining uniform temperature and reducing heat capacity through strategically designed spaces and cooling gas passages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a sintered body with lamination structure is used to control thermal conductivity, then heat transfer to the tool body is reduced, but the manufacturing process becomes complicated
Solution Approach 1:
The pressure plate unit is divided into multiple independent ceramic plates (first ceramic plate, second ceramic plate, third ceramic plate) arranged in layers. Each plate has uniform thermal conductivity, avoiding the need for complex lamination structures while achieving heat isolation through the layered arrangement and air gaps between plates.
Solution Approach 2:
Rod-shaped flexible members are introduced as intermediary elements between the pressure plate unit and the upper pressing member. These members transfer pressure while providing thermal isolation, eliminating the need for complex lamination structures to control heat transfer to the tool body.
2Manufacturing precision
If the thermal expansion coefficient is matched across components, then deformation is reduced, but heat deformation still occurs in portions with temperature gradients
Solution Approach 1:
Different ceramic plates have different thermal conductivities tailored to their specific functions. The first ceramic plate has high thermal conductivity for efficient heating, while the second and third ceramic plates have lower thermal conductivity to isolate heat from the tool body. This local differentiation eliminates heat deformation in each zone while maintaining overall precision.
Solution Approach 2:
The pressure plate unit is segmented into multiple independent ceramic plates with uniform thermal expansion coefficients. This segmentation ensures that each plate expands uniformly without internal temperature gradients, eliminating heat deformation while maintaining flatness of the attractive surface.
3Loss of energy
If the ceramic heater is not thermally isolated from the tool body, then heat transfer is excessive, but reducing thermal conductivity increases heating and cooling times
Solution Approach 1:
The pressure plate unit is segmented into multiple thin ceramic plates rather than using a single thick sintered body. This segmentation reduces thermal mass while maintaining thermal isolation, allowing rapid heating and cooling without excessive heat transfer to the tool body.
Solution Approach 2:
The bonding process uses periodic heating and cooling cycles with the ceramic plates. The high thermal conductivity of the first ceramic plate enables rapid heat input, while the lower conductivity of subsequent plates prevents heat loss to the tool body, achieving efficient periodic thermal processing.
4Loss of energy
If a lamination structure with varying thermal conductivity is used, then heat is transferred to the chip side while isolating the tool body, but the manufacturing complexity increases
Solution Approach 1:
The pressure plate unit is segmented into multiple simple ceramic plates with uniform properties rather than using a complex lamination structure. The layered arrangement of these simple plates, combined with air gaps and flexible members, achieves heat transfer control without manufacturing complexity.
Solution Approach 2:
The thermal conductivity parameter is differentiated across simple ceramic plates rather than creating a complex lamination structure. The first ceramic plate has high thermal conductivity for heating, while subsequent plates have lower conductivity for isolation, achieving heat control through parameter variation in simple components.
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 solution enables precise bonding of electronic components with improved flatness and reduced heating/cooling times, enhancing operational efficiency and accuracy by managing thermal expansion and heat distribution effectively.
Implementation Method 1
a heating member that heats the first block member and the second block member
Implementation Method 2
The first flexible members are connected to the other end surface of the first block member so as to be circumferentially equiangularly spaced about the center line of the first block member. The first flexible members transfer the pressure applied by the first pressure member to the first block member.
Implementation Method 3
The first pressure member applies a pressure to the first block member in a predetermined direction... with a first space therebetween
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A bonding device is provided that is not affected by heat and that is capable of maintaining wafers to be bonded parallel to each other so as to increase and stabilize the accuracy with which the wafers are bonded. A first space M1 is formed between a first block member 12 and a first pressure shaft 22, and a second space M2 is formed between a second block member 28 and a second pressure shaft 42. In this way, little heat is transferred from the first block member 12 and the second block member 28 to the first pressure shaft 22 and the second pressure shaft 42, respectively, and therefore, a substantially uniform temperature is maintained inside the first block member 12 and the second block member 28. Stresses caused by a difference between thermal expansion of the first block member 12 and the second block member 28 and thermal expansion of the first pressure shaft 22 and the second pressure shaft 42 are relieved by deflection of the first support pillar members 20 and the second support pillar members 40. In this way, the flatness of a surface of the first block member 12 for grasping a first wafer W1 and the flatness of a surface of the second block member 28 for grasping a second wafer W2 can be maintained.