Semiconductor Workpiece Temperature Measurement via Thermal Expansion
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Solution Overview
Problem
Current temperature measurement techniques for silicon workpieces in semiconductor processes are limited by environmental constraints, such as impracticality of thermocouples for moving workpieces and difficulties with thermal contact, and the optical properties of silicon make infrared techniques unreliable.
Innovation Solution
A system that measures the temperature of a workpiece by detecting its thermal expansion using a light source and sensor, with a controller determining the temperature based on changes in dimension, which can be applied during semiconductor processes like orientation and ion implantation, without relying on infrared methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If thermocouples are attached to the workpiece for temperature measurement, then temperature data can be obtained, but the workpiece must be stationary and good thermal contact must be established
Solution Approach 1:
The patent replaces mechanical/thermal contact-based thermocouple measurement with an optical measurement system that uses light interaction to detect workpiece properties. The system employs a light source, light sensor, and processor to measure workpiece characteristics optically, eliminating the need for physical thermal contact and enabling measurement of moving workpieces.
2Measurement precision
If thermocouples are mounted to the supporting structure for temperature measurement, then temperature data can be obtained, but the supporting structure temperature may differ from workpiece temperature due to poor thermal contact
Solution Approach 1:
The patent replaces thermal contact-based measurement with optical measurement that directly interacts with the workpiece. The light sensor detects properties of the workpiece itself through light interaction, providing reliable temperature data without dependence on thermal contact quality between the supporting structure and workpiece.
3Ease of operation
If infrared techniques are used for temperature measurement, then non-contact measurement is possible, but the optical properties of silicon make the measurement difficult or impossible
Solution Approach 1:
The patent changes the measurement parameter from infrared radiation detection to optical property detection. Instead of measuring infrared emission which is affected by silicon's optical properties, the system uses a light source and sensor to detect changes in light interaction with the workpiece, which correlates with temperature but is not limited by silicon's infrared characteristics.
4Measurement precision
If test workpieces are used to empirically measure temperature, then temperature data can be obtained, but the measurement is assumed representative of all workpieces and may not reflect actual workpiece temperature
Solution Approach 1:
The patent enables the actual workpiece to serve as its own measurement target. The light source and sensor directly interact with the workpiece being processed, allowing the workpiece itself to provide measurement data about its own temperature and properties, eliminating the need for separate test workpieces and assumptions about representativeness.
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 provides accurate and reliable temperature measurement of silicon workpieces during processing, enhancing throughput by integrating temperature determination into existing processes without adding complexity or time, and allowing for precise temperature control.
Implementation Method 1
measuring the amount of expansion in the workpiece due to thermal expansion
Implementation Method 2
a light source and a light sensor are disposed on opposite sides of the workpiece. The total intensity of the signal received by the light sensor may be indicative of the dimension of the workpiece
Data Source
AI summary
An improved system and method of measuring the temperature of a workpiece being processed is disclosed. The temperature measurement system determines a temperature of a workpiece by measuring the amount of expansion in the workpiece due to thermal expansion. The amount of expansion may be measured using a number of different techniques. In certain embodiments, a light source and a light sensor are disposed on opposite sides of the workpiece. The total intensity of the signal received by the light sensor may be indicative of the dimension of the workpiece. In another embodiment, an optical micrometer may be used. In another embodiment, a light sensor may be used in conjunction with a separate device that measures the position of the workpiece.