Saw Street Probe Pads for Wafer Trimming Without Larger Dies
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Solution Overview
Problem
The reduction in integrated circuit size has made it impossible to accommodate probe pads within the die area for testing and trimming, leading to reduced device yield due to the need for steal primary dies, which occupy valuable operational die space, and the inefficiency of laser trimming methods.
Innovation Solution
The implementation of trimmable or programmable components with probe pads located outside the die, such as in the saw streets, allowing for electrical connection through conductors, and the use of segmented or continuous seal rings to prevent damage and moisture ingress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If probe pads are located within the die area, then testing and trimming can be performed, but the die size increases and operational die space is reduced
Solution Approach 1:
The probe pads are extracted from the die area and relocated to the saw street region. This separation allows the die to maintain its minimal operational size while the probe pads reside in the previously wasted space between dies, enabling testing and trimming without increasing die area.
Solution Approach 2:
The probe pads are positioned in a different spatial dimension (the saw street region between dies) rather than within the die boundary. This dimensional relocation utilizes the inter-die space that was previously unused, resolving the conflict between testing capability and die size.
2Reliability
If steal primary dies are used for testing, then probe pads can be accommodated, but valuable operational die space is occupied
Solution Approach 1:
The testing function is extracted from the die area by placing probe pads in the saw street. This eliminates the need for steal primary dies, as the probe pads in the saw street can serve all dies in the field without requiring dedicated test dies, thereby maximizing device yield.
Solution Approach 2:
The probe pads located in the saw street serve a universal function for testing and trimming multiple dies simultaneously. Instead of requiring separate steal primary dies for each die, the shared probe pad infrastructure in the saw street provides multi-die testing capability, increasing overall productivity.
3Reliability
If laser trimming is used, then trimming can be performed, but the process is inefficient and time-consuming
Solution Approach 1:
The mechanical laser trimming process is replaced with an electrical trimming method. By providing electrical access to trimmable components through probe pads in the saw street, the trimming can be performed electronically during wafer-level testing, significantly reducing trimming time and improving efficiency compared to sequential laser trimming.
Data Source
AI summary
A semiconductor wafer comprising a first die including a first integrated circuit having a trimmable or programmable component. The trimmable or programmable component is configured to be trimmed or permanently altered in response to an electrical signal. The semiconductor wafer also includes a saw street arranged adjacent to the first die, and at least one probe pad electrically connected to the trimmable or programmable component. The at least one probe pad is arranged in the saw street.