Fabrication Tool Calibration Using Etch Rate for Low-Temperature Etching
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Solution Overview
Problem
There is a growing need for precision etching of layer structures in semiconductor processing as integrated circuits scale towards smaller features and increased aspect ratios, necessitating improved precision and higher selectivity, while conventional temperature sensors struggle to operate accurately in low-temperature regimes, leading to variability and lower fidelity across different fabrication tools.
Innovation Solution
A calibration process is implemented to reduce chamber-to-chamber variability by using optimized and well-characterized process parameter sensitized recipes, determining chamber variability, and generating offset parameters to align fabrication tools with a standardized tool, particularly for low-temperature etch processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional temperature sensors are used in low-temperature etch processes, then the fabrication process can be performed, but temperature measurement accuracy deteriorates leading to variability between fabrication tools
Solution Approach 1:
The patent changes the measurement parameter from direct temperature sensing to measuring etch rate, which can be accurately determined through process monitoring. By measuring the etch rate and using the known relationship between temperature and etch rate for the calibrated recipe, the system indirectly determines temperature with high accuracy, avoiding the limitations of conventional temperature sensors in low-temperature regimes.
Solution Approach 2:
The patent introduces etch rate as an intermediary parameter between temperature control and measurement. Instead of directly measuring temperature with problematic sensors, the system measures etch rate (which can be accurately monitored) and uses the calibrated relationship to infer temperature, thereby achieving accurate temperature measurement without relying on faulty direct sensors.
2Manufacturing precision
If precision etching is required for smaller features and increased aspect ratios, then manufacturing precision improves, but process variability between chambers worsens
Solution Approach 1:
The patent performs preliminary calibration by measuring etch rates at multiple known temperature points for each chamber and establishing a unique temperature-etch rate relationship (calibration curve) for each chamber before production use. This preliminary action characterizes each chamber's specific behavior, enabling accurate temperature determination and compensating for chamber-to-chamber variations during subsequent precision etching operations.
Solution Approach 2:
The patent transforms the approach from directly controlling and measuring temperature to controlling and measuring etch rate, which serves as a more reliable proxy for temperature in the low-temperature regime. By using etch rate as the controlled parameter and leveraging the calibrated relationship, the system achieves better manufacturing precision while compensating for chamber variability.
3Productivity
If multiple fabrication tools are used to increase productivity, then output increases, but variability between tools increases
Solution Approach 1:
The patent creates a universal calibration methodology that can be applied to multiple fabrication tools (chambers) of the same type. By establishing calibration curves for each tool using the same recipe and procedure, the system enables consistent temperature measurement and control across the entire fleet of tools, allowing them to be used interchangeably with confidence, thereby maintaining reliability while increasing productivity.
Data Source
AI summary
A method for calibrating a fabrication system including selecting, from multiple recipes, a calibration recipe including a first process parameter for performing a fabrication process on a substrate, including: for each recipe and for two or more substrates, characterization data representative of the fabrication process performed on the two or more substrates using the recipe is received. A second process parameter is determined from the first and second states of the substrates, and a process relationship is determined between the first process parameter and the second process parameter for the recipe. The calibration recipe is selected from the multiple recipes based on the respective process relationships, a threshold variation for the process relationship is determined between the first and the second process parameter; and the calibration recipe and the threshold variation are provided for calibrating the fabrication system.