Ultra-Thin Semiconductor Chip Module Fabrication via Back Grinding
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Solution Overview
Problem
The existing methods for fabricating bump-type image sensor modules are limited by the minimum wafer thickness of 350 μm, making it difficult to produce ultra-thin semiconductor chip modules, whereas wire bonding methods can achieve thinner wafers due to back grinding.
Innovation Solution
A method involving forming a bump on a substrate with a pad, applying a protection layer, and then reducing the substrate thickness through grinding, while exposing the bump by removing the protection layer, allowing for the creation of micro-sized and ultra-thin semiconductor chip modules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bump type image sensor module is fabricated using conventional methods with UBM layer formation through sputtering, then the module provides good electrical connection and reliability, but the minimum wafer thickness is limited to 350 μm
Solution Approach 1:
The patent extracts and removes the UBM (under bump metallurgy) layer formation process from the conventional bump type fabrication method. By eliminating the sputtering-based UBM layer deposition, the patent enables wafer thickness reduction below the conventional 350 μm minimum while maintaining bump electrical connections through alternative means.
Solution Approach 2:
The patent changes the physical and chemical parameters of the wafer by removing the UBM layer formation step, which allows the wafer thickness parameter to be reduced from the conventional 350 μm minimum to thinner dimensions while still achieving functional bump connections.
2Length of stationary object
If the wafer thickness is reduced below 350 μm in bump type modules, then ultra-thin modules can be achieved, but the conventional UBM layer formation process cannot be applied
Solution Approach 1:
The patent extracts the UBM layer formation process from the fabrication sequence, eliminating the sputtering step that would add complexity and cost. This extraction simplifies the overall manufacturing process while enabling ultra-thin wafer fabrication.
Solution Approach 2:
The patent performs preliminary actions by forming bumps directly on the substrate without requiring pre-formed UBM layers. This resequencing and simplification of the fabrication process makes ultra-thin module production more manufacturable.
3Length of stationary object
If wire bonding method is used instead of bump type, then thinner wafers under 250 μm can be achieved through back grinding, but the module size is larger
Solution Approach 1:
The patent inverts the conventional approach by applying back grinding to bump type modules rather than wire bonding modules. Traditionally, back grinding is associated with wire bonding, but the patent successfully applies it to bump type fabrication to achieve thinness while maintaining the compact size advantage of bump technology.
Solution Approach 2:
The patent changes the thickness parameter of the wafer by implementing back grinding in the bump type fabrication process, enabling the wafer thickness to be reduced to under 250 μm while maintaining the module's compact bump-type structure.
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 enables the fabrication of micro-sized and ultra-thin semiconductor chip modules by reducing the substrate thickness to approximately 250 μm, overcoming the thickness limitations of traditional bump-type module fabrication.
Implementation Method 1
performing a grinding process on a rear surface of the substrate to reduce a thickness of the substrate
Data Source
AI summary
A method for fabricating a module of a semiconductor chip is provided. The method includes the steps of: forming a bump on a substrate provided with a pad; forming a protection layer over the bump; performing a grinding process on a rear surface of the substrate to reduce a thickness of the substrate; and exposing the bump by removing the protection layer.