Backside Metal Patterning for Precise Die Street Singulation
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Solution Overview
Problem
Existing die singulation systems face challenges in efficiently separating semiconductor die from a thinned substrate while minimizing damage and achieving high precision.
Innovation Solution
The method involves forming a backside metal layer on the substrate, applying a photoresist layer, patterning it along the die street, and etching through the backside metal layer to expose the substrate. This allows for precise removal of substrate material in the die street, either through plasma etching, laser beams, or saw blades, while also removing the seed layer material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional die singulation methods are used, then die can be separated from substrate, but substrate handling increases and damage risk increases
Solution Approach 1:
The patent performs die singulation from the backside of the substrate rather than the front side. The method includes forming a backside metal layer on the backside of the substrate, applying photoresist over this backside metal layer, patterning the photoresist along die streets, and etching through the backside metal layer to remove substrate material in the die streets. This inversion of the singulation process eliminates the need for complex front-side handling and alignment, reducing substrate manipulation steps and associated damage risks while improving die yield
2Manufacturing precision
If precise singulation is achieved through multiple processing steps, then singulation precision improves, but process complexity increases
Solution Approach 1:
The patent moves the entire singulation process to the backside dimension of the substrate. By forming the backside metal layer and performing all patterning and etching operations from the backside, the method achieves precise singulation through a simplified single-side process rather than complex multi-side operations, reducing overall process complexity while maintaining high precision
Solution Approach 2:
The backside metal layer is formed in advance before the singulation process. This preliminary action provides a robust foundation for subsequent photoresist application and patterning, enabling precise singulation while simplifying the overall process flow by having the metal layer ready to support the etching operations
3Manufacturing precision
If backside metal layer is etched through to expose substrate, then singulation precision improves, but risk of metal material re-deposition increases
Solution Approach 1:
The patent completely removes the backside metal layer material from the die street regions through the etching process. By extracting all metal material from the singulation paths, the method eliminates the source of potential re-deposition while achieving precise singulation, as there is no remaining metal material to redeposit onto the die surfaces
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 enables efficient and precise singulation of semiconductor die with reduced risk of re-deposition of backside metal material and minimizes substrate handling, thereby reducing damage and increasing die yield.
Implementation Method 1
Patterning the photoresist layer may include exposing the photoresist layer and developing the photoresist layer
Implementation Method 2
Removing substrate material in the die street and removing seed layer material in the die street may include plasma etching
Implementation Method 3
Removing substrate material in the die street may include using either a laser beam or a saw blade
Implementation Method 4
The method may include remote plasma healing a plurality of sidewalls of the plurality of die after singulating the die
Data Source
AI summary
Implementations of methods of singulating a plurality of die included in a substrate may include forming a plurality of die on a first side of a substrate, forming a backside metal layer on a second side of a substrate, applying a photoresist layer over the backside metal layer, patterning the photoresist layer along a die street of the substrate, and etching through the backside metal layer located in the die street of the substrate. The substrate may be exposed through the etch. The method may also include singulating the plurality of die included in the substrate through removing a substrate material in the die street.