Photomask Blading Area Test Patterns
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Solution Overview
Problem
Conventional integrated circuit fabrication processes face limitations in testing due to the high cost of additional photomasks and the impracticality of forming test structures on scribe lines, which are long and thin, restricting the number of test patterns that can be formed on each photomask.
Innovation Solution
The method involves forming test patterns in the blading areas of photomasks, allowing these patterns to be transferred to semiconductor substrates for testing without requiring additional photomasks, thereby increasing the number of test structures that can be formed without increasing the number of photomasks used in the fabrication process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If test patterns are formed on scribe lines, then testing can be performed, but the number of test patterns is limited due to the long and thin shape of scribe lines
Solution Approach 1:
The patent moves test patterns from the one-dimensional scribe lines to the two-dimensional blading areas surrounding die regions. This dimensional expansion provides significantly more space for forming test patterns, allowing multiple test structures to be created without being constrained by the limited linear space of scribe lines.
2Quantity of substance
If additional photomasks are purchased for testing, then more test patterns can be formed, but the cost increases significantly
Solution Approach 1:
The patent makes the blading areas of existing photomasks multi-functional by using them for both their traditional purpose (edge coverage during exposure) and as additional space for test patterns. This allows the same photomask to serve both production and testing functions, eliminating the need for separate test photomasks and reducing overall costs.
3Quantity of substance
If blading areas are used for test patterns, then more test structures can be formed without additional photomasks, but the photomask design becomes more complex
Solution Approach 1:
The patent segments the photomask into distinct functional regions: die regions for production patterns, blading areas for test patterns, and scribe lines for alignment. This segmentation allows test patterns to be added to blading areas without interfering with the production patterns in die regions, managing design complexity through clear spatial separation of functions.
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 enables more test structures to be created on semiconductor substrates using existing photomasks, reducing the need for additional masks and lowering costs, while allowing for comprehensive testing of integrated circuit designs and manufacturing processes.
Implementation Method 1
The photomask is exposed to transfer the test pattern to a semiconductor substrate
Data Source
AI summary
A photomask and a method for forming a photomask are disclosed in which die regions that define features for a process step of a semiconductor fabrication process are formed on a photomask and a test pattern for a different process step is formed in a blading area of the photomask. Also, a method for forming test structures is disclosed in which the photomask is exposed to transfer the test pattern to a semiconductor substrate. The process step that is associated with the test pattern is then performed, forming a test structure on the semiconductor substrate. By utilizing blading areas of photomasks and including test patterns for different process steps on the same photomask, more test structures can be obtained, without the need to generate additional photomasks for testing purposes.