Wafer Bonding Apparatus Central Deformation Control
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Solution Overview
Problem
Conventional wafer bonding processes suffer from misalignment and bubble defects due to inadequate control over the bonding time and deformation of wafers, leading to inefficient bonding and potential defects in semiconductor packages.
Innovation Solution
A wafer bonding apparatus with a bonding initiator to deform the upper wafer and a bonding controller to control the bonding speed, ensuring the upper wafer is restored to its original shape before bonding the peripheral portions, using a gas injector to maintain a controlled atmosphere and prevent vapor condensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the bonding pressure is applied to the central portion of the upper wafer to initiate central bonding, then the bonding process starts from the center, but the peripheral portions of the wafers are not properly aligned due to wafer deformation
Solution Approach 1:
The patent applies preliminary action by using a bonding initiator to pre-deform the upper wafer into a concave shape before the bonding process begins. This pre-deformation ensures that when bonding pressure is applied, the wafer maintains proper alignment with the lower wafer throughout the bonding process, preventing misalignment issues that would otherwise occur due to elastic recovery during bonding.
Solution Approach 2:
The patent changes the shape parameter of the upper wafer by deforming it into a concave configuration using the bonding initiator. This parameter change (from flat to concave) allows the wafer to compensate for elastic deformation during bonding, maintaining alignment precision between the upper and lower wafers throughout the bonding process.
2Productivity
If the bonding time is controlled based on wafer elasticity and distance, then the bonding process completes, but vapor condensation occurs on the wafer surfaces causing bubble defects
Solution Approach 1:
The patent applies preliminary action by pre-heating the wafer surfaces before the bonding process begins. This pre-heating ensures that the wafer surfaces maintain a temperature above the dew point throughout the bonding process, preventing vapor condensation and bubble defect formation even when bonding time is reduced to increase productivity.
3Manufacturing precision
If the securing vacuum pressure is turned off when central bonding initiates, then the bonding process progresses, but the upper wafer oscillates and deforms causing misalignment
Solution Approach 1:
The patent applies preliminary action by pre-deforming the upper wafer into a concave shape using the bonding initiator before releasing the securing vacuum pressure. This pre-deformation compensates for the wafer's elastic recovery that occurs when vacuum is released, preventing oscillation and maintaining alignment precision throughout the bonding process without extending bonding time.
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 ensures accurate alignment and minimizes misalignment and bubble defects, allowing for a more efficient and reliable bonding process by controlling the bonding speed and atmosphere within the wafer bonding apparatus.
Implementation Method 1
a bonding initiator for pressuring a central portion of the upper wafer until the central portion of the upper wafer reaches a central portion of the lower wafer, thereby initiating a bonding process of the upper and the lower wafers by deforming the upper wafer
Implementation Method 2
a bonding controller for controlling a bonding speed between a peripheral portion of the upper wafer and a peripheral portion of the lower wafer such that the upper wafer becomes un-deformed prior to bonding the peripheral portion of the upper wafer and the peripheral portion of the lower wafer
Data Source
AI summary
A wafer bonding apparatus including: a lower chuck to which a lower wafer is secured at a peripheral portion of the lower chuck; an upper chuck to which an upper wafer is secured; a bonding initiator for pressuring a central portion of the upper wafer until the central portion of the upper wafer reaches a central portion of the lower wafer, thereby initiating a bonding process of the upper and the lower wafers by deforming the upper wafer; and a bonding controller for controlling a bonding speed between a peripheral portion of the upper wafer and a peripheral portion of the lower wafer such that the upper wafer becomes un-deformed prior to bonding the peripheral portion of the upper wafer and the peripheral portion of the lower wafer.