Lithographic Structure for Line Space Dimension Measurement
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Solution Overview
Problem
The challenge in semiconductor manufacturing is maintaining consistent critical dimensions (CDs) during photolithography processes, especially as technology advances and wafer fabrication approaches sub-micron levels, while minimizing the reduction in throughput time and avoiding additional costs.
Innovation Solution
A lithographic structure and method for measuring line and space dimensions on a substrate, utilizing a frame with specific arrays of lines and spaces, and a method to determine exposure doses by plotting length versus exposure curves, allowing for accurate measurement and adjustment of CDs without adversely affecting throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional measurement methods are used to measure line and space dimensions, then measurement can be performed, but measurement precision is insufficient and cannot accurately detect process variations
Solution Approach 1:
The measurement structure is segmented into multiple distinct regions: a first region with lines and spaces of a first width, and a second region with lines and spaces of a second width. This segmentation allows independent measurement of different feature sizes, enabling detection of process variations affecting different dimensional scales differently, thereby improving measurement precision for critical dimensions.
Solution Approach 2:
The invention introduces a new dimension of measurement by incorporating both width variations (first width and second width) and length variations into the measurement structure. By measuring both the widths and lengths of features in different regions, the method transforms a single-dimension measurement into a multi-dimensional measurement system, enhancing the ability to detect and quantify process-induced dimensional changes.
2Measurement precision
If advanced measurement structures are implemented to improve CD measurement accuracy, then measurement precision improves, but device complexity and manufacturing cost increase
Solution Approach 1:
The lithographic structure serves multiple functions: it acts as both a process monitor and a measurement target. The same pattern structure used in photolithography also functions as the measurement artifact, eliminating the need for separate measurement structures. This multi-functionality reduces device complexity while maintaining high measurement precision for critical dimensions.
Solution Approach 2:
The measurement structure is designed to be self-measuring through its inherent geometric relationships. The known dimensional relationships between the first and second regions, combined with the measurable features (lines, spaces, openings), allow the structure to provide its own measurement data without requiring external reference standards or complex calibration procedures, thereby simplifying the measurement system.
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
Enables precise measurement and control of CDs, reducing the impact of process variations and equipment errors, thereby ensuring consistent device performance while maintaining efficient fabrication processes.
Implementation Method 1
One important step in the manufacturing of such devices is the formation of devices, or portions thereof, using photolithography and etching processes. In photolithography, a wafer substrate is coated with a light-sensitive material called photo-resist. Next, the wafer is exposed to light; the light striking the wafer is passed through a mask plate.
Data Source
AI summary
There is a structure and method for measuring the lengths of lines and spaces in semiconductor process. In an example embodiment, a lithographic structure (400) comprises, a frame (450). The frame includes a top inside edge, a top outside edge, a bottom inside edge, a bottom outside edge, a left inside edge, a left outside edge, a right inside edge, and a right outside edge. There is a first array of lines (430) and spaces, the first array having end of lines (420b) and end of spaces (430a). The lines have a first line width and the spaces have a first space width; the end of spaces are at a first distance (10) from the top outside edge of the frame (450), the end of lines are at a second distance (20) from the top outside edge of the frame (450). A first opening (410a) is a third distance (30) from the bottom outside edge of the frame and a second opening (410b) is a fourth distance (40) from the bottom outside edge of the frame.