Semiconductor Wafer Back Grinding with Cured Resin Planarization
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Solution Overview
Problem
The existing methods for thinning semiconductor wafers, such as mechanical grinding and chemical surface treatment, often result in wafer breakage due to asperities, and the need for costly support bases during planarization, increasing manufacturing costs.
Innovation Solution
A method involving the application of a viscous material to the wafer's asperity surface, followed by curing and grinding, where the variation in distance between the cured material and a reference surface is controlled to 15% or less of the in-plane average, eliminating the need for support bases and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mechanical grinding is performed on the back surface of the semiconductor wafer, then thinning of the wafer is achieved, but wafer breakage occurs due to asperities on the front surface
Solution Approach 1:
The resin is applied to the front surface of the semiconductor wafer before mechanical grinding of the back surface. This preliminary action creates a protective layer that compensates for asperities and prevents wafer breakage during the subsequent grinding process, thereby maintaining wafer integrity while achieving precise thinning
Solution Approach 2:
A resin layer is introduced as an intermediary substance between the grinding process and the wafer structure. The resin acts as a mediator that absorbs mechanical stress and protects the wafer from direct contact with grinding forces, preventing breakage while allowing controlled thinning
2Manufacturing precision
If a support base is stacked on the uncured resin surface for planarization, then the front surface planarity is improved, but manufacturing cost increases
Solution Approach 1:
The resin layer itself is utilized to provide the planarization function. By controlling the resin application thickness and curing process, the resin self-levels to create a planar front surface without requiring an external support base, thereby eliminating additional manufacturing steps and reducing costs
Solution Approach 2:
The support base component is extracted or removed from the manufacturing process. Instead of using a separate support base structure, the resin layer alone performs the planarization function, simplifying the overall process and reducing material costs
3Reliability
If the variation in resin layer thickness is reduced to 15% or less, then wafer protection during grinding is improved, but resin application precision requirements increase
Solution Approach 1:
The acceptance criterion for resin thickness variation is defined as 15% or less of the average thickness. This parameter specification balances the need for adequate wafer protection with the practical capabilities of resin application processes, ensuring reliable protection without requiring excessively tight tolerances that would be difficult to achieve
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 enhances the fracture strength of the semiconductor wafer, reduces the thickness of the fractured layer, and decreases manufacturing costs by eliminating the need for support base stacking and chemical grinding, while maintaining wafer integrity.
Implementation Method 1
a curing step of curing the viscous material
Implementation Method 2
mechanical grinding (polishing), such as back grinding and polishing
Data Source
AI summary
A method includes a step of applying a viscous material to a front surface having asperities thereon of a semiconductor wafer, a step of curing the viscous material, and a step of grinding a back surface of the semiconductor wafer on which the cured viscous material has been provided, a reference surface and projections constitute the asperities on the front surface, and a variation in distance between a surface of the cured viscous material and the reference surface is 15% or less of an in-plane average of the distance in the front surface of the semiconductor wafer. A fractured layer after grinding of the back surface can thereby be thinned, so that a fracture strength of the semiconductor wafer can be increased.