Semiconductor Die Back Metal Separation via Fluid Ablation
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Solution Overview
Problem
The semiconductor industry faces challenges in singulating die from a wafer due to non-compatibility of plasma dicing with wafer backside layers, which requires effective removal of backside layers from singulation lines to facilitate subsequent processing, while minimizing damage and contamination, and improving manufacturing throughput and cost-effectiveness.
Innovation Solution
A method involving plasma etching to form narrow singulation lines and subsequent fluid machining to remove backside layers using a pressurized fluid ablation process, with adjustable process parameters and zone-specific fluid jet techniques to ensure efficient separation without damaging the die, utilizing a Bosch process and fluid jet ablation with varying pressures and speeds depending on the zone's distance from the center of the wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma dicing is used to singulate die, then throughput is increased and scribe line width is reduced, but backside layers cannot be effectively removed from singulation lines
Solution Approach 1:
The patent combines plasma dicing with a subsequent fluid machining process to achieve both narrow scribe lines and effective backside layer removal. The plasma process creates the initial singulation lines, then fluid machining (using water jets or other fluid streams) removes the backside layers from these lines, merging two processes to solve the contradiction between throughput and manufacturability.
Solution Approach 2:
The patent introduces an intermediary fluid machining step that acts as a mediator between plasma dicing and subsequent assembly processes. This intermediary process removes the backside layers that plasma dicing leaves behind, enabling the transition from high-speed singulation to precise assembly operations.
2Ease of manufacture
If conventional scribing is used to singulate die, then backside layers can be removed from singulation lines, but scribe line width is large and throughput is reduced
Solution Approach 1:
The patent segments the singulation process into two distinct stages: first, plasma dicing creates narrow singulation lines to maximize die yield; second, fluid machining selectively removes backside layers from these lines. This segmentation allows each process to be optimized independently, avoiding the trade-off present in conventional single-step scribing.
Solution Approach 2:
The patent replaces the mechanical scribing process with a plasma-based process followed by fluid machining. This substitution eliminates the need for wide mechanical cutting paths while achieving the same backside layer removal function, thereby increasing throughput without sacrificing manufacturability.
3Loss of time
If plasma dicing is used to singulate die, then processing time is reduced, but damage or contamination to die may occur
Solution Approach 1:
The patent uses fluid machining (pneumatic or hydraulic jets) to remove backside layers from singulation lines. This fluid-based approach is less likely to cause mechanical damage to the die compared to mechanical scribing, while still achieving the necessary material removal. The fluid stream can be precisely controlled to avoid contaminating 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 method enables efficient and cost-effective removal of backside layers, reducing processing time and minimizing damage to the die, thereby enhancing manufacturing throughput and supporting reclaim efforts while maintaining the integrity of the semiconductor die.
Implementation Method 1
plasma dicing has had manufacturing implementation challenges
Implementation Method 2
the etch process has been unable to effectively remove the backside layers from the singulation lines
Implementation Method 3
subsequent processing, such as pick-and-place and assembly processes
Implementation Method 4
A method involving plasma etching to form narrow singulation lines and subsequent fluid machining to remove backside layers using a pressurized fluid ablation process
Data Source
AI summary
In one embodiment, semiconductor die are singulated from a semiconductor wafer having a backmetal layer by placing the semiconductor wafer onto a carrier tape with the backmetal layer adjacent the carrier tape, forming singulation lines through the semiconductor wafer to expose the backmetal layer within the singulation lines, and separating portions of the backmetal layer using a fluid.