Multiple-Exposure Patterning for Unique Die Identification
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Solution Overview
Problem
Conventional photolithographic processes in integrated circuit manufacturing cannot provide unique identification for each die on a wafer, limiting yield analysis and tracking during and after the test, assembly, and packaging processes.
Innovation Solution
A multiple-exposure patterning technique is used to create a die identification pattern on a lower layer of the integrated circuit, with a marker positioned in a subsequent upper layer to uniquely identify each die's location on the wafer, employing a two-pass exposure method to ensure the marker is accurately placed relative to the identification pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If a single-stepped reticle set exposure is used in photolithography, then the manufacturing process is simple and efficient, but unique identification for each die cannot be provided
Solution Approach 1:
The patterning process is divided into two separate exposure steps: first exposing the main die pattern, then exposing the marker pattern. This segmentation allows the marker to be independently positioned at different locations for each die, providing unique identification while maintaining overall process efficiency
Solution Approach 2:
The marker pattern is prepared in advance on the reticle at multiple predetermined locations, corresponding to different die positions. During the second exposure step, the reticle is repositioned to expose the appropriate marker location for each die, enabling pre-planned unique identification without adding complex real-time positioning systems
2Reliability
If multiple-exposure patterning is used to provide unique die identification, then each die can be uniquely identified, but the patterning process becomes more complex
Solution Approach 1:
The marker exposure is merged with the existing photolithography process flow by using the same exposure tool and resist layer. The two-exposure sequence is integrated into a single processing step without requiring separate tooling or additional material deposition, thereby maintaining high productivity while achieving reliable die identification
Solution Approach 2:
The same reticle pattern is used for both the main die exposure and the marker exposure, with the reticle simply repositioned between exposures. This copying approach eliminates the need for separate reticles or complex alignment systems, preserving manufacturing throughput while enabling unique die identification through marker positioning
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 allows for unique identification of each die on the wafer, enhancing yield analysis and tracking capabilities during and after the test, assembly, and packaging processes by providing a distinct marker for each die's location.
Implementation Method 1
photolithography, which involves passing light through a reticle (also referred to as a mask) to expose a layer's image for one or more die on a wafer
Data Source
AI summary
Systems and methods are disclosed herein to provide die identification. For example, in accordance with an embodiment of the present invention, a wafer patterning technique is disclosed that provides multiple-exposure patterning to provide a unique identifying mark for each die on a wafer.