Semiconductor Die Thinning via Etch Stop Layer
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Solution Overview
Problem
The production of thin semiconductor dies is challenging due to their fragility and warpage, which affects yield and accuracy in processing, especially in applications where final chip thickness influences performance.
Innovation Solution
A method involving a semiconductor wafer with a device layer, an inner etch stop layer, and a lower handle layer, where the inner etch stop layer is used to selectively etch the device layer and handle layer, allowing for the formation of thin dies without mechanical processing that could introduce cracks, and subsequent encapsulation to provide protection and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If mechanical processing is used to thin the semiconductor die, then the die thickness is reduced, but cracks and breakage occur due to mechanical stress
Solution Approach 1:
The patent replaces mechanical processing methods (such as grinding or sawing) with a chemical etching process. The etch stop layer is selectively removed through chemical etching to achieve the desired thinning without applying mechanical stress that would cause cracks or breakage in the semiconductor die.
Solution Approach 2:
The patent introduces an etch stop layer as an intermediary element between the semiconductor die and the handling process. This layer can be selectively removed through chemical etching to achieve precise thickness control without mechanically stressing the die, thereby preventing cracks and breakage.
2Reliability
If the die thickness is reduced to improve performance, then channel resistance decreases, but the die becomes more fragile and prone to breakage
Solution Approach 1:
The patent replaces mechanical thinning processes with chemical etching to achieve the required thin die thickness for low channel resistance while avoiding mechanical stress that would cause breakage in these ultra-thin structures.
Solution Approach 2:
The patent changes the processing parameter from mechanical removal to chemical etching, enabling precise control of die thickness at the micrometer and sub-micrometer level required for optimal device performance while maintaining structural integrity through stress-free processing.
3Manufacturing precision
If thin dies are produced to meet performance requirements, then channel resistance is reduced, but warpage occurs during processing
Solution Approach 1:
The patent replaces mechanical processing with chemical etching, which uniformly removes material without inducing the mechanical stresses and forces that cause warpage in thin die structures, thereby maintaining die flatness throughout the manufacturing process.
Solution Approach 2:
The etch stop layer serves as a self-aligning reference plane that automatically defines the final die thickness and ensures uniform etching across the wafer surface, eliminating the need for complex mechanical positioning and reducing warpage risks.
4Productivity
If conventional handling methods are used for thin dies, then production can proceed, but yield decreases due to breakage
Solution Approach 1:
The patent performs the die thinning and encapsulation in a predetermined sequence before final die separation and handling. The etch stop layer is removed and dies are encapsulated while still attached to the wafer, providing collective support that prevents breakage during subsequent processing steps and maximizes yield.
Solution Approach 2:
The patent combines multiple processing steps (thinning, encapsulation, and separation) into an integrated process flow where thin dies are encapsulated en masse while still attached to the wafer substrate, providing structural support during handling and significantly reducing breakage losses.
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 production of thin semiconductor dies with consistent thickness and improved ruggedness, reducing the risk of breakage and warpage, thereby enhancing yield and performance by ensuring precise thickness and minimizing mechanical stress.
Implementation Method 1
the etch stop layer is removed to expose a backside of the semiconductor device layer
Data Source
AI summary
A method of producing a semiconductor device is provided. The method includes: providing a semiconductor wafer, the wafer including an upper layer of a semiconductor material, an inner etch stop layer and a lower layer; forming a plurality of functional areas in the upper layer; performing a selective first etch process on the upper layer so as to separate the plurality of functional areas from each other by trenches etched through the upper layer, the first etch process being substantially stopped by the inner etch stop layer; and removing the lower layer by a second etch process, the second etch process being substantially stopped by the inner etch stop layer.