Wafer Dicing Plasma Etching Kerf Lines Edge Chipping
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Solution Overview
Problem
Current wafer dicing methods, such as mechanical sawing and laser dicing, result in chipping and cracking near the outer edges of wafers, reducing die reliability and yield, while plasma dicing can cause delamination issues with smaller die due to their larger contact area with adhesive underlayers.
Innovation Solution
The method involves etching kerf lines within an interior region of the wafer to singulate die and wafer edge areas, with additional kerf lines extending between kerf line segments and the circumferential edge to minimize edge chipping and cracking, allowing for more controlled separation and easier packaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If mechanical sawing is used for wafer dicing, then high speed rotation enables efficient separation of die, but chipping and cracking occur near the outer edges of the wafer reducing die reliability and yield
Solution Approach 1:
The patent replaces the mechanical sawing system with a plasma-based etching system. Instead of using a high-speed rotating mechanical saw that causes chipping and cracking, the invention uses plasma to etch kerf lines through the wafer, achieving die separation without mechanical contact. This substitution eliminates the harmful mechanical stresses while maintaining efficient through-silicon etching capability.
2Ease of manufacture
If laser dicing is used for wafer separation, then non-contact cutting is achieved, but intense thermal effects cause crack formation and deposits near the outer edges reducing die reliability and yield
Solution Approach 1:
The patent changes the physical parameters of the energy-based dicing approach by replacing laser (thermal energy) with plasma (chemical energy). Instead of using intense laser beams that cause thermal cracking and deposits, the invention employs plasma chemistry to etch the wafer material, achieving non-contact cutting without the harmful thermal effects that compromise die reliability.
3Manufacturing precision
If plasma dicing is used with lithographic process extending kerf lines to the edge of the wafer, then direct plasma access enables complete etching, but smaller die with smaller contact area are prone to chipping and cracking and delamination from adhesive underlayer
Solution Approach 1:
The patent applies local quality by differentiating the treatment of different wafer regions. Instead of uniformly extending kerf lines to the wafer edge, the invention segments the kerf lines into interior regions and edge regions. The edge region kerf lines are specifically designed to terminate before reaching the wafer periphery, creating a protective unetched margin that prevents chipping and delamination of smaller die while maintaining precise plasma etching control in interior regions.
4Manufacturing precision
If kerf lines are extended to the edge of the wafer in plasma dicing, then complete singulation is achieved, but an unetched ring of material remains around the edge requiring additional process step for removal
Solution Approach 1:
The patent extracts the problematic unetched ring requirement by strategically positioning kerf line endpoints. Instead of extending all kerf lines to the wafer edge, the invention terminates edge region kerf lines before they reach the periphery, naturally eliminating the need for an additional process step to remove an unetched ring. This extraction of the unnecessary material removal step simplifies the overall process while maintaining complete singulation functionality.
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 reduces chipping and cracking, enhances die reliability, and facilitates easier packaging by minimizing the unetched ring around the wafer edge, meeting zero-defect standards in automotive and industrial applications.
Implementation Method 1
Plasma dicing is based on a multiplexed deep reactive ion etching (DRIE) technique
Data Source
AI summary
A method of dicing a wafer includes providing a wafer and etching the wafer to singulate die between kerf line segments defined within an interior region of the wafer and to singulate a plurality of wafer edge areas between the kerf line segments and a circumferential edge of the wafer. Each one of the plurality of wafer edge areas is singulated by kerf lines that each extend between one of two endpoints of one of the kerf line segments and the circumferential edge of the wafer.