Semiconductor Wafer Thermal Control for Faster Accurate Mass Metrology
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Solution Overview
Problem
High-accuracy semiconductor wafer mass metrology is hindered by temperature variations between the wafer and the measurement apparatus, leading to errors in mass measurement due to temperature differences and air density changes, which are exacerbated by the need for prolonged cooling times that reduce processing throughput.
Innovation Solution
The method involves controlling the cooling or heating of semiconductor wafers based on their initial temperature, optimizing the duration and rate of thermal transfer to match the wafer temperature to a predetermined range, thereby skipping unnecessary cooling or heating steps and improving processing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the semiconductor wafer is cooled using a passive thermal transfer plate to equalise temperature to within ±0.1°C, then measurement accuracy is improved, but processing time increases
Solution Approach 1:
The method performs preliminary cooling of the semiconductor wafer using an active thermal transfer plate before the mass measurement process. By pre-cooling the wafer to reduce the temperature difference with the measurement balance to less than 1°C (preferably 0.1°C or less), the subsequent measurement can be completed more quickly while maintaining accuracy, thus reducing total processing time
Solution Approach 2:
The invention replaces passive thermal transfer (relying on natural heat conduction) with active thermal transfer using a thermoelectric cooler (Peltier device). This active cooling system provides controlled and accelerated heat removal from the wafer, significantly reducing the time required to achieve thermal equilibrium compared to passive methods
2Measurement precision
If a fixed cooling duration is applied to all wafers, then temperature equalisation is achieved, but processing throughput decreases
Solution Approach 1:
The invention implements dynamic control of the cooling process by continuously monitoring the wafer temperature during cooling and adjusting the cooling power and duration accordingly. The controller modifies cooling parameters in real-time based on measured temperature, allowing each wafer to be cooled to the required temperature uniformity (±0.1°C) in the minimum necessary time, thereby optimizing both measurement accuracy and processing throughput
Solution Approach 2:
The system incorporates temperature sensing during the cooling process and uses this feedback information to control the cooling duration and intensity. By measuring the wafer temperature and comparing it to the target temperature range, the controller adjusts the cooling process to achieve optimal temperature uniformity while minimizing cooling time, thus improving overall productivity
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 approach reduces measurement errors by minimizing temperature-related inaccuracies and increases the throughput and productivity of semiconductor wafer processing by tailoring thermal treatment to the specific temperature of each wafer, ensuring accurate mass measurements while reducing processing time.
Implementation Method 1
a passive thermal transfer plate (7) positioned on top of the measurement chamber (5). The passive thermal transfer plate (7) is in direct physical contact with the measurement chamber (5) and is substantially in thermal equilibrium with the measurement chamber (5)
Implementation Method 2
air currents (e.g. convection currents) may be generated in the air in the measurement enclosure, which may affect the measurement output
Implementation Method 3
the air in the measurement enclosure may be heated, changing its density and pressure and therefore the buoyancy force exerted on the semiconductor wafer by the air
Data Source
Figure 1~2
Figure 3
AI summary
A semiconductor wafer mass metrology method comprising: controlling the temperature of a semiconductor waferby: detecting information relating to the temperature of the semiconductor wafer; and controlling cooling or heating of the semiconductor wafer based on the detected information relating to the temperature of the semiconductor wafer; wherein controlling the cooling or heating of the semiconductor wafer comprises controlling a duration of the cooling or heating of the semiconductor wafer; and subsequently loading the semiconductor wafer onto a measurement area of a semiconductor wafer mass metrology apparatus.