Single-Cell In-Die Metrology Targets for Overlapping Layer Measurement
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Solution Overview
Problem
Semiconductor metrology faces challenges in measurement accuracy, real-estate use, and throughput, particularly in small areas such as scribe lines and critical layers of semiconductor devices.
Innovation Solution
Design of metrology targets with at least two overlapping structures that are measurable in a mutually exclusive manner at different optical conditions, allowing for independent measurements of different layers, reducing target size to less than 5 μm×5 μm and enabling in-die overlay measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If traditional metrology targets are used with spatial separation between layers, then measurement accuracy is maintained, but real estate consumption increases and target size must be larger
Solution Approach 1:
The patent transitions from spatial separation (2D plane) to optical condition separation (wavelength/focus dimensions). Multiple layers are measured by assigning each layer to specific optical conditions rather than physically separating them in space, enabling overlapping structures to be measured independently without increasing target area.
Solution Approach 2:
The patent changes measurement parameters (optical conditions including wavelength and focus) to distinguish between overlapping layers. By varying these parameters, the system can selectively measure different layers through the same physical space, eliminating the need for spatial separation and reducing target real estate requirements.
2Productivity
If multiple layers are measured simultaneously with spatial separation, then throughput is improved, but real estate consumption increases significantly
Solution Approach 1:
The patent merges multiple layer measurements into a single overlapping target structure. Instead of requiring separate spatial zones for each layer measurement, the system combines multiple layers in the same physical space and uses optical condition differentiation to enable simultaneous or sequential measurement of all layers within the same target area.
Solution Approach 2:
The patent creates a universal target structure where a single overlapping configuration serves multiple measurement functions. The same physical target area can measure multiple layers by switching optical conditions, making the target multi-functional and eliminating the need for separate dedicated areas for each layer measurement.
3Area of stationary object
If optical conditions are used to distinguish layers without spatial separation, then real estate use is reduced, but measurement complexity increases
Solution Approach 1:
The patent uses controlled changes in optical parameters (wavelength, focus) to simplify the measurement process. By systematically varying these parameters according to a predetermined scheme, the system can selectively isolate and measure different layers, transforming a potentially complex multi-layer measurement problem into a controlled parameter variation process.
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
Significantly reduces the required real estate for metrology measurements, enhances measurement accuracy, and improves throughput by using optical conditions to distinguish between layers without spatial separation, making them more efficient and scalable.
Implementation Method 1
at least two overlapping structures configured to be measurable in a mutually exclusive manner at least at two different corresponding optical conditions
Data Source
AI summary
Metrology targets and methods are provided, which comprise at least two overlapping structures configured to be measurable in a mutually exclusive manner at least at two different corresponding optical conditions. The targets may be single cell targets which are measured at different optical conditions which enable independent measurements of the different layers of the target. Accordingly, the targets may be designed to be very small, and be located in-die for providing accurate metrology measured of complex devices.