Wafer Bonding Thermal Expansion Alignment
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Solution Overview
Problem
The existing wafer bonding process faces issues with horizontal position deviation and scaling due to warping of wafers, leading to product yield deterioration and increased costs from time-consuming external inspections.
Innovation Solution
A method involving temperature adjustment of one substrate to match the expanded diameter of the other, followed by precise imaging and positioning adjustments within the bonding apparatus to ensure accurate alignment and bonding, eliminating the need for external inspection devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the central portion of the upper wafer is pressed by the pressing member to bring it into contact with the lower wafer, then bonding can be performed, but the upper wafer becomes warped and stretched causing horizontal position deviation
Solution Approach 1:
The lower wafer is pre-heated before bonding to expand it in advance. This preliminary expansion counteracts the stretching that occurs during bonding, preventing horizontal position deviation. The lower wafer is heated to a temperature higher than the upper wafer before the bonding process begins, causing thermal expansion that compensates for the deformation caused by pressing.
Solution Approach 2:
The temperature of the lower wafer is changed to control its expansion. By adjusting the temperature of the lower wafer to be higher than the upper wafer, the lower wafer expands thermally. This parameter change (temperature) directly affects the dimensional stability and prevents position deviation during bonding.
2Manufacturing precision
If the lower wafer is heated to expand it to compensate for upper wafer stretching, then horizontal position deviation is reduced, but additional heating equipment and process complexity are required
Solution Approach 1:
The heating mechanism serves dual purposes: it heats the lower wafer for thermal expansion to prevent position deviation, and it also provides the necessary temperature for the bonding process itself. This multi-functionality eliminates the need for separate heating equipment, reducing overall system complexity while maintaining manufacturing precision.
3Manufacturing precision
If external inspection devices are used to verify wafer alignment, then positioning accuracy can be confirmed, but inspection time and manufacturing costs increase
Solution Approach 1:
The bonding apparatus performs its own inspection function using integrated imaging parts. The system captures images of alignment marks on the wafers, automatically calculates horizontal position deviations, and verifies alignment accuracy without requiring external inspection devices. This self-inspection capability reduces both time and cost while maintaining high precision.
4Manufacturing precision
If the lower wafer is heated to expand it, then the diameter of the lower wafer increases to match the stretched upper wafer, but temperature control precision is required
Solution Approach 1:
The system uses imaging parts to capture alignment marks on the wafers and automatically calculates the horizontal position deviation. This feedback information is used to adjust the heating temperature of the lower wafer, ensuring it expands to the precise degree needed to match the upper wafer's stretched diameter, thereby achieving accurate temperature control.
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 effectively suppresses scaling, improves product yield by reducing waste, and lowers manufacturing costs by integrating inspection within the bonding process, ensuring accurate and efficient substrate bonding.
Implementation Method 1
the lower wafer is expanded by adjusting a temperature thereof prior to holding the lower wafer with the lower chuck
Implementation Method 2
imaging a plurality of reference points of the second substrate held in the second holding part with a first imaging part
Implementation Method 3
the bonding device bonds the wafers using a Van der Waals force and hydrogen bonding (an inter-molecular force)
Implementation Method 4
the bonding device bonds the wafers using a Van der Waals force and hydrogen bonding (an inter-molecular force)
Data Source
AI summary
There is provided a method of bonding substrates to each other, which includes: holding a first substrate on a lower surface of a first holding part; adjusting a temperature of a second substrate by a temperature adjusting part to become higher than a temperature of the first substrate; holding the second substrate on an upper surface of a second holding part; inspecting a state of the second substrate by imaging a plurality of reference points of the second substrate with a first imaging part, measuring positions of the reference points, and comparing a measurement result with a predetermined permissible range; and pressing a central portion of the first substrate with a pressing member, bringing the central portion of the first substrate into contact with a central portion of the second substrate, and sequentially bonding the first substrate and the second substrate.