Ultra-thin Semiconductor Die via Anisotropic Etching
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Solution Overview
Problem
The existing methods for thinning semiconductor devices, such as back grinding followed by saw cutting, often result in mechanical damage and limited thinning due to the mechanical forces involved, which can lead to chip breakage and further damage during the singulation process.
Innovation Solution
A method where a mask layer with open trench regions is formed on the backside of the semiconductor substrate, allowing for simultaneous thinning and singulation through anisotropic etching, which continues until the trenches break through to the frontside, enabling precise control of the final die thickness and minimizing mechanical stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If back grinding is used to thin the semiconductor die, then the die thickness is reduced, but the mechanical forces cause the wafer to chip or break
Solution Approach 1:
The patent replaces the mechanical back grinding process with a chemical etching process. The etch selectively removes material from the backside of the wafer through chemical reactions, eliminating the mechanical forces that cause chipping and breaking while achieving the desired thinning effect
Solution Approach 2:
The patent changes the fundamental parameter of the thinning process from mechanical removal to chemical removal. By controlling etch time, etch rate, and etch selectivity, the process achieves precise thickness control without the mechanical stress inherent in grinding
2Length of moving object
If the die is thinned before singulation, then the die thickness is reduced, but the likelihood of damage during singulation increases
Solution Approach 1:
The patent merges the thinning process and singulation process into a single integrated operation. The etch simultaneously thins the die and creates separation trenches between adjacent dies, eliminating the need for a separate singulation step that would expose the thinned dies to mechanical damage
Solution Approach 2:
The patent performs preliminary etching of separation trenches before complete singulation. These pre-formed trenches provide mechanical support and defined separation paths during the final singulation step, reducing the risk of damage to thinned dies
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 allows for the thinning of semiconductor substrates to a precise thickness while reducing the risk of mechanical damage during singulation, enabling the production of ultra-thin semiconductor devices with improved performance and handling characteristics.
Implementation Method 1
An anisotropic etch applied to the backside results in a pattern transfer of the trench regions onto the backside of the substrate
Implementation Method 2
etch of the backside of the substrate is performed to thin the wafer evenly over the backside surface
Data Source
AI summary
In accordance with a specific embodiment, a method of processing a semiconductor substrate is disclosed whereby the substrate is thinned, and the dice formed on the substrate are singulated by a common process. Trench regions are formed on a backside of the substrate. An isotropic etch of the backside results in a thinning of the substrate while maintaining the depth of the trenches, thereby facilitating singulation of the die.