Wafer Spacing via Intermediary Dispersion to Reduce Attraction Forces
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Solution Overview
Problem
The increasing surface forces between thin, flat silicon wafers due to reduced thickness and adhesive bonding make it difficult to separate them without breaking, as the attraction forces, including fluid cohesion and surface tension, hinder the singulation process.
Innovation Solution
Introducing spacers between wafers before removing the adhesive maintains a distance and reduces attraction forces, allowing for easier separation by using spherical or non-spherical bodies dispersed in a fluid, such as a washing solution, with varying sizes and densities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wafer thickness is reduced to lower manufacturing costs, then manufacturing cost decreases, but surface forces increase and mechanical resistance decreases making separation difficult
Solution Approach 1:
The patent introduces spacers between wafers before the adhesive is removed, performing the spacing action in advance. This preliminary placement of spacers ensures that when the adhesive bonding is released, the wafers are already separated by a sufficient distance to overcome surface forces, making the subsequent separation process easier despite reduced wafer thickness
Solution Approach 2:
The patent uses spacers as intermediary objects placed between adjacent wafers. These spacers act as mediators that maintain a controlled distance between wafer surfaces, preventing direct contact and reducing the harmful surface forces (fluid cohesion, material adhesion, surface tension, viscous shear) that make separation difficult
2Ease of manufacture
If wafer thickness is reduced, then manufacturing cost decreases, but attraction forces between wafers increase
Solution Approach 1:
The spacers are introduced before adhesive removal to preemptively establish the necessary separation distance. This preliminary spacing prevents the wafers from coming into close contact where attraction forces would be strongest, thereby reducing the overall attraction forces acting on thin wafers
Solution Approach 2:
The spacers serve as intermediary elements that physically separate the wafer surfaces. By placing these intermediaries between wafers, the patent reduces the direct surface-to-surface interaction that generates attraction forces (fluid cohesion, material adhesion, surface tension, viscous shear), thereby lowering the total attractive force on reduced-thickness wafers
3Ease of operation
If spacers are introduced between wafers, then separation becomes easier, but device complexity increases
Solution Approach 1:
The spacers are designed to be self-introducing elements that automatically position themselves between wafers during the manufacturing process. This self-service approach eliminates the need for complex external mechanisms to place spacers, reducing device complexity while still achieving the benefit of easier separation
Solution Approach 2:
The spacers appear to be simple, inexpensive objects that are used temporarily during the separation process. By using cheap, simple spacer elements rather than complex mechanical systems, the patent achieves easier separation without significantly increasing device or process complexity
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 method effectively reduces attraction forces between wafers, facilitating their separation by maintaining a distance and enhancing the singulation process, benefiting both manual and automatic methods.
Implementation Method 1
The attraction forces are caused by fluid cohesion, material adhesion, surface tensions, viscous shear, etc.
Implementation Method 2
After the wafers have been sawed they are still glued (with adhesive bonding) to the carrying structure on one side
Implementation Method 3
the spacers consist of multiple bodies dispersed in a fluid. This fluid can be a liquid or gas
Data Source
AI summary
A method for reducing attraction forces between wafers (4) is provided. This method includes the step of, after sawing and before dissolution of the adhesive (5), introducing spacers (6) between wafers (4). A wafer singulation method and an agent for use in the method are also provided.