Die Pickup Sequencing by Wafer Region for Package Yield
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Solution Overview
Problem
The existing methods for picking up dies from a diced wafer in semiconductor package manufacturing are inefficient, leading to low yields due to the mixing of dies from high-failure and low-failure regions, which can result in defective semiconductor packages.
Innovation Solution
A method of classifying the pickup region into specific zones such as outermost, adjacent, and inner regions, and picking up dies in a sequential order along defined trajectories, ensuring that high-failure region dies are concentrated on separate substrates from low-failure region dies, thereby improving yield and reducing process time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dies are picked up randomly from the diced wafer without region classification, then the pickup process is simple and fast, but the yield decreases due to mixing high-failure and low-failure region dies
Solution Approach 1:
The diced wafer is divided into multiple regions (first region, second region, third region, etc.) based on their distance from the center. The pickup process is segmented to handle each region separately, with outer regions (higher failure rates) processed before inner regions (lower failure rates). This segmentation allows classification of dies by region while maintaining an organized pickup sequence that improves yield without excessive complexity.
2Productivity
If dies from different regions are mixed on the same substrate, then the substrate utilization is high, but the product quality decreases due to defective packages
Solution Approach 1:
Different regions of the diced wafer are assigned different handling priorities based on their failure rates. Outer regions with higher failure rates are picked up first and placed on substrates, while inner regions with lower failure rates are picked up later. This local quality approach ensures that high-failure dies are isolated on certain substrates while low-failure dies are concentrated on other substrates, improving overall package quality while maintaining substrate utilization.
3Reliability
If the pickup process handles outer regions first, then high-failure region dies are segregated early, but the process time increases due to sequential region handling
Solution Approach 1:
The method performs preliminary classification of the diced wafer into regions before the actual pickup process. By pre-defining the region boundaries and pickup sequence (first region, second region, third region, etc.), the system prepares the pickup path in advance. This preliminary action allows the pickup head to follow an optimized trajectory that segregates high-failure dies early while minimizing unnecessary movements, thus reducing overall process time compared to unoptimized sequential handling.
Data Source
AI summary
A method of picking up a die may include classifying a pickup region of a diced wafer, in which targeted pickup dies are placed, into first to n-th regions and performing a pickup step on dies in the first to n-th regions. The first region may include first dies, which are outermost dies of the targeted pickup dies. An (x+1)-th region may include regions, occupied by dies adjacent to at least one of x-th dies in an x-th region and proximate to a center of the pickup region in relation to the x-th region, n may be a natural number, and x may be an arbitrary natural number that is smaller than the n. The n-th region may have a rectangular shape, and a quantity of n-th dies in the n-th region in contact with a short side of the n-th region may be one or two.