Plasma Wafer Dicing with Stealth Cracks for Die Integrity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional mechanical sawing techniques for dicing semiconductor wafers are time-consuming and can cause vibrations leading to cracks in dies, affecting yield and reliability.
Innovation Solution
Plasma dicing method involving a die substrate with a BEOL dielectric, passivation layer, and die attach film, where stealth dicing creates a modified layer with cracks to facilitate singulation using lateral force, avoiding notching and improving die strength and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If mechanical sawing is used to dice wafers, then the wafer can be separated into individual dies, but the process takes time and causes vibration leading to cracks
Solution Approach 1:
The patent replaces the mechanical sawing system with a plasma-based system. Instead of using a physical saw blade that mechanically cuts through the wafer, the invention uses plasma etching to remove material and create separation channels. This substitution eliminates the vibration and mechanical contact that cause die cracking while maintaining the ability to separate dies efficiently.
Solution Approach 2:
The patent changes the physical state and parameters of the cutting process from mechanical force to plasma chemistry. By controlling plasma parameters such as gas composition, power, and etch chemistry, the process achieves clean separation without mechanical stress. The plasma process parameters are optimized to etch through the wafer material selectively along predetermined dicing lines.
2Productivity
If plasma dicing is used to dice wafers, then throughput improves and vibration is eliminated, but additional plasma etching steps may be required
Solution Approach 1:
The patent combines multiple functions into the plasma dicing process. The plasma etching step simultaneously performs material removal for separation, defines the dicing channel geometry, and creates clean separation surfaces. By merging these functions into a single integrated process step, the invention avoids the need for separate notching or additional etching steps that would increase process complexity.
Solution Approach 2:
The plasma dicing process is designed to be universal, handling various wafer materials and thicknesses with a single process platform. The plasma chemistry can be adjusted to etch through different semiconductor materials, and the process simultaneously achieves separation, surface preparation, and contamination removal, making it a multi-functional solution that reduces overall process complexity.
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
Enhances throughput and reliability by eliminating vibration-induced cracks and improving die strength, stability, and shear, while avoiding the need for additional plasma etching and reducing cross-contamination.
Implementation Method 1
Plasma dicing entails mounting a wafer onto a wafer ring and inserting the wafer ring with the wafer into a plasma chamber for etching
Data Source
AI summary
Reliable plasma dicing of a processed wafer with a die attach film (DAF) attached to the bottom wafer surface to singulate it into individual dies is disclosed. Laser processing is employed to form mask openings in a passivation stack of a processed wafer to serve as a dicing mask. Laser processing is employed to form a modified layer with cracks on a bottom portion of the wafer. Plasma dicing partially dices the processed wafer to about the modified layer. The dicing tape is expanded laterally away from the center of the partially diced processed wafer, singulating it into individual dies. Singulation of the partially plasma diced processed wafer is facilitated by the modified layer.