Monitor Substrate Temperature Measurement via Lattice Disorder
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Solution Overview
Problem
Conventional methods for monitoring temperature in low-temperature thermal processes, such as silicidation, face challenges in precise temperature determination due to the sensitivity of sheet resistance to metal layer thickness and the inability to recycle monitor wafers, and lack of local temperature uniformity assessment.
Innovation Solution
A method involving a monitor substrate subjected to ion implantation, with thermal wave intensity measurements before and after the thermal process, allowing for precise temperature calculation through changes in lattice disorder, and the use of an isolating layer to prevent material reaction, enabling precise temperature control and wafer recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a monitor wafer with cobalt silicide layer is used for temperature monitoring, then the temperature can be derived based on sheet resistance measurement, but the monitor wafer cannot be recycled and production cost increases
Solution Approach 1:
The patent applies the discarding and recovering principle by using a separate monitor wafer that can be discarded after a single use. The monitor wafer is specifically designed for temperature monitoring purposes and does not need to be reused, thereby simplifying the process and avoiding contamination issues that would prevent recycling of wafers used for device fabrication
Solution Approach 2:
The patent segments the monitoring function from the device fabrication process by using a dedicated monitor wafer. This separate monitor wafer contains only the metal layer and oxide layer structure needed for temperature sensing, allowing it to be processed independently and discarded after providing temperature data, while the main wafers continue through the fabrication process
2Measurement precision
If cobalt silicide sheet resistance is used to determine temperature, then temperature can be derived, but the sensitivity is low and real temperature cannot be determined precisely
Solution Approach 1:
The patent applies parameter changes by modifying the monitor wafer structure to include a thin oxide layer (50-200 Å) between the metal layer and substrate, and by controlling the metal layer thickness (500-2000 Å). These parameter changes create a system where sheet resistance becomes highly sensitive to temperature variations, enabling precise temperature determination with sensitivity much higher than conventional cobalt silicide monitoring
3Device complexity
If cobalt silicide is formed as a whole on the monitor wafer, then the monitoring process is simple, but local sheet resistance values cannot be determined to check temperature uniformity
Solution Approach 1:
The patent applies local quality by creating a monitor wafer with a uniform metal layer and thin oxide layer structure that allows for localized measurements. The simplified structure enables measurement of local sheet resistance values at different positions on the wafer surface, providing temperature uniformity information across the processing area while maintaining process simplicity
4Ease of manufacture
If the monitor substrate structure is simplified, then the process is easier, but the sensitivity to temperature changes is reduced
Solution Approach 1:
The patent achieves both ease of manufacture and high temperature sensitivity through careful parameter selection: a thin oxide layer (50-200 Å) that is simple to deposit but creates high sensitivity, and a controlled metal layer thickness (500-2000 Å) that balances fabrication simplicity with temperature response. The simplified two-layer structure (metal + thin oxide) is easy to manufacture while the specific thickness parameters ensure high temperature sensitivity
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 method allows for precise temperature monitoring and control in low-temperature thermal processes, enabling better control of sheet resistance and assessment of temperature uniformity, with the added benefit of wafer recyclability and reduced production costs.
Implementation Method 1
A monitor substrate is provided and subject to ion implantation
Implementation Method 2
a characteristic parameter of the monitor substrate correlated to the disorder degree of the lattice structure of the same, such as a thermal wave intensity of the same in a thermal wave analysis, is measured
Implementation Method 3
The monitor substrate is then subject to the thermal process, and the same characteristic parameter of the monitor substrate is measured again to obtain a second value
Data Source
AI summary
A method for monitoring a temperature in a thermal process is described. A monitor substrate is provided and subject to ion implantation, and a characteristic parameter of the monitor substrate correlated to the disorder degree of the lattice structure of the same is measured to obtain a first value. The monitor substrate is then subject to the thermal process, and the characteristic parameter of the monitor substrate is measured again to obtain a second value. The difference between the first value and the second value is calculated to derive the temperature in the thermal process.