Plasma Chamber Temperature Control Using Chiller Fluid Feedback
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Solution Overview
Problem
In semiconductor manufacturing, accurately controlling the temperature within a plasma processing chamber is challenging due to difficulties in directly measuring temperature with sensors, requiring indirect estimation methods.
Innovation Solution
A chamber temperature control method and apparatus that measure fluid temperatures using a chiller temperature sensor, calculate predicted chamber temperatures using specific functions, and adjust heater temperatures based on errors calculated by a PID controller to maintain the desired temperature ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a temperature sensor is provided in the processing space to directly measure the temperature, then the measurement precision would be improved, but it becomes difficult to measure the temperature accurately when plasma is being generated
Solution Approach 1:
The patent uses an intermediary substance (gas or liquid) that circulates through the chamber to transfer thermal energy from the plasma processing zone to a temperature sensor located outside the plasma environment. This intermediary allows indirect measurement of plasma zone temperature without exposing the sensor to conditions that would prevent accurate measurement or damage the sensor.
Solution Approach 2:
The patent replaces the direct mechanical/physical contact measurement approach (temperature sensor in plasma zone) with a thermal field-based indirect measurement approach. By measuring temperature differences in the circulating fluid and using thermal conduction principles, the system substitutes direct sensing with a field-based measurement method that avoids the plasma environment's harmful effects on sensors.
2Difficulty of detecting and measuring
If indirect estimation methods are used to obtain temperature in the processing space, then the difficulty of measuring temperature during plasma generation is reduced, but the measurement precision deteriorates
Solution Approach 1:
The patent implements a feedback control system where temperature sensors monitor the circulating fluid's temperature at multiple points, and this information is fed back to a control algorithm that continuously adjusts the estimation of the plasma processing zone temperature. This feedback loop compensates for estimation errors and maintains measurement precision despite using indirect methods.
Solution Approach 2:
The patent changes the measurement parameters from direct temperature sensing in the plasma zone to measuring temperature differences in the circulating fluid. By monitoring parameters such as inlet and outlet fluid temperatures, flow rate, and thermal conductivity, the system transforms an unmeasurable parameter (plasma zone temperature) into measurable parameters that can be used to calculate the desired temperature with high precision.
3Loss of information
If multiple temperature sensors are provided in different portions of the chamber, then the temperature distribution information is improved, but the device complexity increases
Solution Approach 1:
The patent makes the circulating fluid serve multiple functions simultaneously: it acts as a thermal conductor to transfer heat from the plasma zone, as a transport medium to carry thermal energy to external sensors, and as a cooling agent for the chamber components. This multi-functionality allows a single fluid circulation system to provide comprehensive temperature distribution information without requiring separate sensing systems for each function.
Solution Approach 2:
The patent creates thermal copies of the plasma processing zone temperature conditions by measuring the temperature of the circulating fluid that has been in contact with the processing zones. Instead of placing sensors directly in each processing zone, the system uses the fluid as a carrier to copy the thermal information from multiple zones to external measurement points, reducing system complexity while maintaining information completeness.
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
Effectively estimates and controls the temperature in plasma processing chambers, ensuring precise temperature management for wafer processing by using fluid temperature measurements and adjusting heaters accordingly.
Implementation Method 1
measuring a first fluid temperature when fluid is supplied to the support unit and a second fluid temperature when the fluid is retrieved from the support unit by using a chiller temperature sensor attached to a chiller
Implementation Method 2
adjusting temperatures of heaters provided in the chamber based on the calculated error
Implementation Method 3
initiating processing on the wafer by using plasma within the chamber
Data Source
AI summary
Provided is a chamber temperature control method for controlling a temperature of a chamber that performs processing on a wafer mounted on a support unit by using plasma, the method including: initiating processing on the wafer by using plasma within the chamber, measuring a first fluid temperature when fluid is supplied to the support unit and a second fluid temperature when the fluid is retrieved from the support unit by using a chiller temperature sensor attached to a chiller configured to supply the fluid to the support unit or retrieve the fluid from the support unit through a chiller pipe, determining set temperatures to be compared with reference temperatures of the chamber by determining whether an RF power source for generating the plasma is operating, calculating an error by comparing the set temperatures to the reference temperatures, and adjusting temperatures of heaters.