Wafer Backside Layer Separation via Plasma and Mechanical Scribing
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Solution Overview
Problem
The semiconductor industry faces challenges in singulating die from a wafer due to non-compatibility with wafer backside layers, particularly back metal layers, which are not effectively removed or separated by existing methods like plasma dicing, leading to reduced throughput and manufacturing capacity.
Innovation Solution
A method involving plasma etching to form narrow singulation lines that stop proximate to the backside layer, combined with mechanical devices applying localized pressure to separate the backside layers, allowing for efficient removal while minimizing damage to the die.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma dicing is used to singulate die, then throughput and manufacturing capacity are improved, but backside layers such as back metal layers cannot be effectively removed or separated
Solution Approach 1:
The patent segments the singulation process into two distinct stages: first, plasma dicing creates initial separation lines in the wafer; second, a mechanical scribing wheel completes the separation by removing backside layers. This segmentation allows each method to perform its optimal function - plasma for speed and mechanical for complete material removal.
Solution Approach 2:
The patent introduces a mechanical scribing wheel as an intermediary tool that bridges the gap between plasma dicing capabilities and complete backside layer removal requirements. The scribing wheel acts as a mediator that performs the function neither plasma alone nor traditional mechanical dicing can achieve efficiently.
2Reliability
If traditional scribing with diamond cutting wheel is used, then backside layers are effectively removed, but scribe grid width is large and processing time exceeds one hour per wafer
Solution Approach 1:
The patent applies partial action by using plasma dicing to perform the initial separation and remove most of the backside layer material, then using mechanical scribing only for the remaining material. This partial application of mechanical action reduces processing time while achieving complete removal.
Solution Approach 2:
The patent substitutes mechanical dicing with a hybrid approach where plasma energy replaces mechanical cutting for the majority of the separation process. Only a minimal mechanical intervention is required to complete the separation, dramatically reducing processing time from over one hour to a fraction of that time.
3Length of moving object
If plasma dicing is used, then narrower singulation lines are achieved, but backside layers remain attached and interfere with subsequent processing
Solution Approach 1:
The patent segments the material removal function between plasma (for narrow line creation) and mechanical scribing (for complete backside layer removal). This segmentation allows narrow singulation lines to be formed while ensuring complete separation of backside layers for subsequent processing compatibility.
Solution Approach 2:
The patent performs preliminary plasma dicing to create narrow singulation lines and remove most backside material before final mechanical scribing. This preliminary action prepares the wafer for subsequent processing by establishing precise separation lines while leaving minimal material for the final mechanical step to remove.
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 cost-effective and efficient separation of backside layers, improving manufacturing throughput and reducing yield loss by preventing cracks from propagating into active die areas.
Implementation Method 1
A method involves plasma etching to form narrow singulation lines that stop proximate to the backside layer
Implementation Method 2
mechanical devices applying localized pressure to separate the backside layers
Data Source
AI summary
A method for forming an electronic device includes providing a wafer having a plurality of die formed as part of the wafer and separated from each other by spaces. A layer of material is disposed atop a major surface of the wafer and the layer of material is placed adjacent to first carrier substrate comprising a first adhesive layer. The wafer is singulated through the spaces to form singulation lines. A second carrier substrate comprising a second adhesive layer is placed onto an opposite major surface of the wafer. The method includes moving a mechanical device adjacent to and in a direction generally parallel to one of the first carrier substrate or the second carrier substrate to separate the layer of material in the singulation lines. In one example, the second adhesive layer has an adhesive strength that is less than that of the first adhesive layer.