Substrate Breakage Detection in Thermal Processing
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Solution Overview
Problem
Millisecond anneal systems in semiconductor processing face challenges in detecting substrate breakage during thermal processing, leading to potential contamination and scrap of unprocessed wafers due to vibrations and stress induced by rapid heating and cooling.
Innovation Solution
A process for breakage detection in thermal processing systems involves accessing temperature measurements during the cool-down period, estimating cooling model metrics, and determining a breakage detection signal based on these metrics to prevent further processing and initiate corrective actions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If rapid heating is applied to achieve millisecond anneal, then heat treatment effectiveness is improved, but substrate breakage risk increases due to thermal stress and vibrations
Solution Approach 1:
The system performs preliminary detection of substrate breakage during the cool-down phase by analyzing temperature measurements against a cooling model. This early detection allows the system to identify broken substrates before they contaminate subsequent processing, preventing waste and maintaining reliability while preserving the rapid heating capability.
Solution Approach 2:
The system implements feedback by continuously monitoring temperature measurements during cooling and comparing them to predicted values from a cooling model. When deviations indicate breakage, the system generates a breakage detection signal that triggers corrective actions, creating a closed-loop control system that maintains substrate integrity despite rapid thermal cycling.
2Measurement precision
If continuous monitoring is implemented to detect substrate breakage, then detection accuracy is improved, but system complexity increases
Solution Approach 1:
The system uses the substrate's own thermal cooling process as the detection mechanism. By analyzing the natural cool-down temperature measurements against a pre-established cooling model, the system detects breakage without requiring additional sensors or complex monitoring hardware. The substrate's thermal behavior serves as both the processing parameter and the detection signal.
Solution Approach 2:
The system detects breakage by monitoring changes in cooling parameters (temperature vs. time relationship) rather than using dedicated detection hardware. When the actual cooling curve deviates from the predicted cooling model, it indicates a change in the substrate's thermal properties due to breakage, providing accurate detection through parameter analysis rather than complex instrumentation.
3Reliability
If breakage detection is performed during cool-down period, then detection reliability is improved, but processing time increases
Solution Approach 1:
The system performs breakage detection during the necessary cool-down period without extending the overall processing time. The temperature measurements taken during cooling serve dual purposes: enabling the substrate to return to a safe temperature and providing the data needed for breakage detection. This continuous useful action eliminates idle time and maintains processing efficiency while ensuring reliable detection.
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 real-time or near-real-time detection of substrate breakage, preventing contamination and ensuring the quality of subsequent wafers by accurately determining whether a substrate has broken during thermal processing.
Implementation Method 1
Millisecond, or ultra-fast, temperature treatment of semiconductor substrates can be achieved using an intense and brief exposure of light to heat the entire top surface of the substrate
Implementation Method 2
The rapid heating of just one surface of the substrate can produce a large temperature gradient through the thickness of the substrate, while the bulk of the substrate maintains the temperature before the light exposure. The bulk of the substrate therefore acts as a heat sink resulting in fast cooling rates of the top surface.
Data Source
AI summary
Apparatus, systems, and processes for substrate breakage detection in a thermal processing system are provided. In one example implementation, a process can include: accessing data indicative of a plurality of temperature measurements for a substrate, the plurality of measurements obtained during a cool down period of a thermal process; estimating one or more metrics associated with a cooling model based at least in part on the data indicative of the plurality of temperature measurements; and determining a breakage detection signal based at least in part on the one or more metrics associated with the cooling model. The breakage detection signal is indicative of whether the substrate has broken during thermal processing.