Chip Code Pattern for Tracing Number Representation
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Solution Overview
Problem
As semiconductor chips become smaller, the limited space on their bottom surface, occupied by solder balls and conductive metal patterns, makes it difficult to laser mark tracing numbers, which are essential for identifying manufacturing history and defect tracing, especially in medical applications.
Innovation Solution
The tracing number is decomposed into lot ID and wafer number, represented by specific code patterns, allowing for their compact representation on the chip's surface without the need for laser marking, using space-efficient designs and materials that can coexist with conductive metal patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If laser marking is used to mark tracing number on chip bottom, then tracing number can be clearly marked, but sufficient marking space cannot be secured on small chips
Solution Approach 1:
The tracing number is segmented into multiple components: lot ID, wafer number, and chip coordinate. Each component is represented by a separate code pattern (first, second, and third code patterns respectively). This segmentation allows the tracing information to be distributed across multiple compact patterns rather than requiring a single large marking area.
Solution Approach 2:
The patent transitions from traditional linear or alphanumeric laser marking to two-dimensional bar code patterns. Each digit or component of the tracing number is represented by a geometric code pattern with specific orientation and arrangement, effectively utilizing spatial dimensions to encode information more densely.
2Productivity
If chip size is reduced to increase integration density, then more functions can be integrated, but space for tracing number marking becomes insufficient
Solution Approach 1:
Instead of directly marking alphanumeric characters which require significant space, the patent uses code patterns that copy or represent the tracing information in a compressed graphical form. Each digit is represented by a geometric pattern that can be recognized and decoded, significantly reducing the space required compared to direct character marking.
Solution Approach 2:
The patent changes the representation parameters from traditional laser-marked alphanumeric characters to geometric code patterns with specific properties (number of lines, orientations, arrangements). This parameter change enables the same information to be encoded in a much smaller physical space.
3Reliability
If tracing number is marked on chip bottom, then defect tracing is enabled, but marking space conflicts with solder balls and conductive metal patterns
Solution Approach 1:
The patent applies different code patterns to different local regions of the chip bottom surface, optimizing the use of available space. Each code pattern is positioned in a specific location avoiding conflicts with solder balls and conductive patterns, and each pattern has specific local characteristics (orientation, size, position) tailored to its placement context.
Data Source
AI summary
A chip comprises a semiconductor substrate having a first side and a second side opposite to the first side, a plurality of conductive metal patterns formed on the first side of the semiconductor substrate, a plurality of solder balls formed on the first side of the semiconductor substrate, and at least one code pattern of a first group and at least one code pattern of a second group formed on the first side of the semiconductor substrate in a space free from the plurality of conductive metal patterns and the plurality of solder balls, wherein the code patterns are visible from a backside of the chip, and wherein a tracing number of the chip is represented by the code patterns.