Substrate Bonding Pressure Equalization to Prevent Air Bubbles
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Solution Overview
Problem
Existing methods fail to fully remove air bubbles between substrates during bonding, leading to reduced bonding strength due to air re-entry during pressure equalization.
Innovation Solution
A two-stage valve system controls the entry of atmospheric air into the bonding chamber, allowing slow and rapid pressure increases to expel existing air bubbles and prevent new bubbles from forming, using a first flow coefficient for slow pressure rise and a second flow coefficient for rapid equalization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If air is rapidly evacuated from the confined chamber to remove air bubbles between substrates, then air bubbles are effectively removed, but air can re-enter during pressure equalization and form new bubbles
Solution Approach 1:
The pressure equalization process is segmented into two distinct stages: a first stage with a first flow coefficient that allows controlled air entry, and a second stage with a second flow coefficient that completes the equalization. This segmentation prevents air bubbles from forming during pressure recovery while maintaining effective air removal during bonding.
Solution Approach 2:
The system dynamically adjusts the flow coefficient of the valve assembly during the bonding process. The flow coefficient is changed from a first value during vacuum bonding to a second value during pressure equalization, allowing the system to adapt to different process requirements and prevent air bubble formation.
2Manufacturing precision
If a confined chamber is used to evacuate air during bonding, then air bubbles are removed from between substrates, but air can re-enter during pressure restoration and affect bonding strength
Solution Approach 1:
The bonding process is completed under vacuum conditions before pressure equalization begins. Air bubbles are removed and bonding is established while the chamber is still evacuated, ensuring that no air can re-enter between the substrates during the subsequent pressure restoration phase.
Solution Approach 2:
The confined chamber maintains a vacuum (inert) environment during the critical bonding phase, preventing air from interfering with the bonding process. The vacuum environment ensures that air bubbles are removed and cannot re-form during the bonding operation.
3Productivity
If pressure is increased rapidly to restore atmospheric pressure, then pressure equalization is achieved quickly, but air can enter between substrates and form bubbles
Solution Approach 1:
The pressure equalization process is divided into two segments with different flow coefficients. The first segment uses a restricted flow coefficient to allow controlled air entry, while the second segment uses a higher flow coefficient to complete the equalization, preventing air bubble formation during the transition.
Solution Approach 2:
The flow coefficient parameter of the valve assembly is changed between two distinct values during the pressure equalization process. This parameter change controls the rate of air entry into the chamber, preventing air bubbles from forming between the bonded substrates.
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 method effectively eliminates air between bonded substrates and prevents re-entry during pressure recovery, enhancing bonding yield and strength.
Implementation Method 1
evacuating air from the confined chamber to vacuum the confined chamber to a predetermined low pressure value
Implementation Method 2
allowing the outside atmosphere air to slowly enter the confined chamber by a first flow coefficient; and allowing the outside atmosphere air to rapidly enter the confined chamber with a second flow coefficient
Data Source
AI summary
A bonding method of substrates for bonding a first substrate and a second substrate. The method includes: placing the first substrate on a holding surface of a holder in a confined chamber; evacuating air from the confined chamber to vacuum the confined chamber to a predetermined low pressure value; placing the second substrate on a top of the first substrate; pressing to the second substrate onto the first substrate; and allowing an outside atmosphere air to slowly enter the confined chamber by a first flow coefficient; and allowing the outside atmosphere air to rapidly enter the confined chamber with a second flow coefficient, wherein the second flow coefficient is greater than the first flow coefficient.