Backside Metal Patterning for Die Singulation
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Solution Overview
Problem
Current die singulation methods face challenges in efficiently separating semiconductor die from a thinned substrate without damaging the substrate or causing re-deposition of metal layers, especially when handling thin substrates and maintaining precise control over the singulation process.
Innovation Solution
The method involves forming a backside metal layer on a substrate, applying an organic layer, creating a groove through the organic layer and partially through the metal layer, and using etching and plasma techniques to singulate the die, while monitoring the process to prevent substrate damage and re-deposition, allowing for precise control and efficient separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional die singulation methods are used to separate semiconductor die from thinned substrate, then die separation is achieved, but substrate damage and metal layer re-deposition occur
Solution Approach 1:
The singulation process is divided into multiple controlled steps: forming grooves through the organic layer and metal layer, selective etching of metal in die streets, and gradual substrate material removal. This segmented approach allows precise control at each stage, preventing uncontrolled substrate damage and metal re-deposition that occurs in conventional single-step singulation methods.
Solution Approach 2:
Before actual singulation, the method performs preliminary actions including forming an organic layer over the metal layer, creating grooves through these layers, and selectively etching metal in die streets. These preparatory steps establish controlled pathways and remove potential contaminants before the final substrate removal, preventing metal re-deposition and substrate damage during singulation.
2Productivity
If conventional singulation methods are used, then die separation is achieved, but metal layer re-deposition occurs
Solution Approach 1:
The method extracts and removes the metal layer selectively from die street regions before substrate singulation. By using etching to remove metal only in die street areas (not over the die), and forming grooves through the organic layer, the patent prevents metal particles from being available to re-deposit on the substrate during subsequent singulation steps, thereby eliminating metal re-deposition contamination.
Solution Approach 2:
The organic layer serves as an intermediary protective barrier between the metal layer and the substrate during singulation. This organic layer is formed over the metal layer, and grooves are formed through it in die streets. During singulation, this organic material prevents direct contact and potential metal re-deposition onto the substrate surface, acting as a protective mediator.
3Reliability
If precise control is implemented to prevent substrate damage, then substrate integrity is improved, but process complexity increases
Solution Approach 1:
The method applies different treatments to different regions of the substrate: die regions receive protective treatment while die street regions undergo selective metal etching and groove formation. This local differentiation allows precise control where needed (in die streets) without unnecessarily complicating the entire process, as the organic layer and groove formation are only applied locally to die street areas.
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 effective singulation of semiconductor die with minimal substrate damage, reduced re-deposition of metal layers, and increased process yield by allowing for precise control and monitoring of the singulation process, particularly beneficial for thin substrates.
Implementation Method 1
The groove may be formed using either a laser beam or a saw blade
Implementation Method 2
Etching may include wet etching through the remaining portion of the backside metal layer
Implementation Method 3
singulating the plurality of die in the substrate through plasma etching at the portion of the substrate exposed by the etching
Implementation Method 4
The method may include remote plasma healing a sidewall of the die
Data Source
AI summary
Implementations of methods of singulating a plurality of die comprised 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 polymer layer over the backside metal layer and forming a groove entirely through the polymer layer and partially through a thickness of the backside metal layer. The groove may be located in a die street of the substrate. The method may also include etching through a remaining portion of the backside metal layer located in the die street, removing the polymer layer, singulating the plurality of die in the substrate by removing substrate material in the die street.