Die Seal Ring with Varying Widths for Sawing Stress Mitigation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing methods for cutting dies from a semiconductor wafer, such as diamond blade sawing and laser grooving, often result in damage like chipping and peeling due to stress, and are costly, with laser cutting being particularly expensive and leaving debris.
Innovation Solution
A die seal ring with varying local widths is implemented around the integrated circuit region of each die, with wider segments corresponding to higher stress areas to mitigate damage during sawing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a uniform width seal ring is used, then the manufacturing process is simple, but the die cannot be effectively protected from stress at high-stress areas
Solution Approach 1:
The seal ring is designed with non-uniform width where the width varies at different angular positions. Specifically, the seal ring has a greater width at angular positions corresponding to high-stress areas (near scribe lines) and a smaller width at angular positions corresponding to low-stress areas (center regions). This local variation in geometry provides enhanced stress resistance where needed while maintaining manufacturing feasibility.
2Reliability
If laser grooving is used to cut dies, then die damage from sawing stress is reduced, but manufacturing cost increases significantly and debris contamination occurs
Solution Approach 1:
The cutting process is divided into two stages: first, laser grooving creates initial separation grooves along the scribe lines to reduce stress concentration; second, diamond blade sawing completes the separation. This segmented approach allows the use of cheaper diamond blade sawing while maintaining the stress-reduction benefits of laser grooving, thereby reducing overall manufacturing cost while preserving die integrity.
3Ease of manufacture
If diamond blade sawing is used, then manufacturing cost is low, but die damage from stress occurs frequently
Solution Approach 1:
Before the diamond blade sawing process, laser grooving is performed to create preliminary grooves along the scribe lines. These pre-formed grooves serve to reduce stress concentration during the subsequent sawing operation. This preliminary action allows the use of cost-effective diamond blade sawing while mitigating the stress-related die damage that would otherwise occur.
Data Source
AI summary
A die seal ring disposed in a die and surrounding an integrated circuit region of the die is described. The die seal ring has at least two different local widths.