Dual Wafer Temperature Sensing Across Doping and Temperature Ranges
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Solution Overview
Problem
Existing semiconductor fabrication processes face challenges in accurately measuring the temperature of substrates with varying doping levels across a wide temperature range due to limitations in pyrometer and transmission-based thermometry, which are inadequate for both heavily and lightly doped silicon wafers at different temperature ranges.
Innovation Solution
A dual-sensor temperature measurement system combining a pyrometer and a transmission-based subsystem, configured to measure thermal radiation and light transmission through the substrate, with sensors positioned in a nearly collinear configuration to cross-reference readings and determine substrate emissivity, enabling accurate temperature measurement across a broad temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If pyrometer is used for temperature measurement, then measurement range is extended, but measurement precision deteriorates for both heavily and lightly doped substrates
Solution Approach 1:
The patent combines two different temperature measurement methods (pyrometer and transmission-based thermometry) into a unified dual-sensor system. Each sensor type compensates for the other's limitations, allowing accurate temperature measurement across the full range for both heavily and lightly doped substrates by selecting the appropriate measurement method based on substrate doping level and temperature range
Solution Approach 2:
The patent introduces an intermediary control system that selects between pyrometer and transmission-based thermometry measurements based on substrate characteristics and temperature range. This intermediary layer resolves the contradiction by directing the appropriate measurement method to each specific measurement scenario, ensuring both wide range and high precision
2Measurement precision
If transmission-based thermometry is used, then measurement precision is improved for lightly doped substrates, but adaptability deteriorates for heavily doped substrates
Solution Approach 1:
The patent creates a universal temperature measurement system that can handle both lightly and heavily doped substrates by integrating two measurement methods. The system automatically adapts its measurement approach based on substrate doping level, achieving multi-functionality that covers the complete range of substrate types and temperature conditions
3Measurement precision
If dual sensor system is implemented, then measurement precision is improved across all substrate types, but device complexity increases
Solution Approach 1:
The dual-sensor system performs self-service by automatically selecting the appropriate measurement method based on substrate characteristics and temperature range. The control system autonomously determines whether to use pyrometer or transmission-based thermometry without requiring manual intervention, thereby managing the complexity internally while maintaining measurement precision
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
The system provides accurate temperature measurement for both heavily and lightly doped substrates from 50 to 400°C or 100 to 600°C, ensuring uniformity and precision in thermal processing.
Implementation Method 1
a first detector configured to measure thermal radiation emitted by the substrate
Implementation Method 2
a second detector configured to measure light transmitted through the substrate
Implementation Method 3
a substrate heater having a plurality of light emitting diodes (LEDs)
Data Source
AI summary
An apparatus may include: (a) a processing chamber including chamber walls and a chamber heater; and (b) a pedestal positioned within the chamber interior and including: (i) a substrate heater having a plurality of light emitting diodes (LEDs), (ii) a window positioned above the substrate heater comprising a material transparent to light from the LEDs, (iii) three or more substrate support pads configured to support a substrate such that the window and the substrate are offset by a nonzero distance; and (iv) a temperature sensor comprising a first detector configured to measure thermal radiation emitted by the substrate, and a second detector configured to measure light transmitted through the substrate.